Method and apparatus for depositing atomic layers on a substrate

ABSTRACT

Method of performing atomic layer deposition. The method comprises supplying a precursor gas towards a substrate, using a deposition head including one or more gas supplies, including a precursor gas supply. The precursor gas reacts near a surface of the substrate for forming an atomic layer. The deposition head has an output face comprising the gas supplies, which at least partly faces the substrate surface during depositing the atomic layer. The output face has a substantially rounded shape defining a movement path of the substrate. The precursor-gas supply is moved relative to the substrate by rotating the deposition head while supplying the precursor gas, for depositing a stack of atomic layers while continuously moving in one direction. The surface of the substrate is kept contactless with the output face by means of a gas bearing.

The invention relates to a method of performing atomic layer depositionon a substrate, which method comprises supplying a precursor gas towardsthe substrate using a deposition head, the deposition head including oneor more gas supplies including a precursor gas supply for supplying theprecursor gas; having the precursor gas react near, e.g. on, a surfaceof the substrate so as to form an atomic layer, the deposition headhaving an output face that at least partly faces the surface of thesubstrate during depositing the atomic layer, the output face beingprovided with the one or more gas supplies and having a substantiallyrounded shape defining a movement path of the substrate, wherein themethod further comprises moving the precursor-gas supply relative to andalong the substrate by rotating the deposition head while supplying theprecursor gas; thus depositing a stack of atomic layers whilecontinuously moving the precursor-gas supply in one direction, whereinmethod is performed while keeping the surface of the substratecontactless with the output face by means of a gas bearing providedusing the one or more gas supplies. The invention further relates to anapparatus for performing the method.

Atomic layer deposition (ALD) is known as a method for depositing amonolayer of target material. Atomic layer deposition differs from forexample chemical vapor deposition in that atomic layer deposition takesat least two consecutive process steps (i.e. half-cycles). A first oneof these self-limited process steps comprises application of a precursorgas on a substrate's surface. A second one of these self-limited processsteps comprises reaction of the precursor material in order to form themonolayer of target material. Atomic layer deposition has the advantageof enabling excellent if not ideal layer thickness control.

However, atomic layer deposition is a layer-by-layer deposition process,and the consecutive processing steps are to be performed for thedepositing of each monolayer. In between, a step of purging is usuallyperformed to prevent the precursor and reactive gasses to react atlocations where this is not intended (e.g. in the processing apparatussuch as near an outlet). The depositing of each monolayer is thereforerelatively slow. As a result, application of atomic layer deposition fordepositing layers with a certain thickness larger than about 10nanometers usually is rather time-consuming, because numerous atomiclayers need to be stacked for obtaining such a layer thickness.

In recent years, there has been an increased interest in industrializingatomic layer deposition processes by finding ways to decrease theprocessing times involved with ALD processes. For example, the insightof spatially separating the consecutive processing steps (instead of theconventional temporal separation) has brought down the processing timesconsiderably. Spatial separation is obtained by moving a substrate fromone processing chamber to another, separated by a gas curtain. Anadditional purging step is then no longer required, allowing the ALDprocess to be performed much faster.

However, although spatial ALD resembles an important improvement, afurther hurdle towards industrialization still remains untaken. Theconventional ALD processes, including conventional spatial ALDprocesses, are confined to substrates of a limited size. As may beappreciated, an objective for industrialization is to provide an ALDprocess that may be applied to surfaces of any size. One possiblesolution to achieve this goal has been the development of a roll-to-roll(R2R) atomic layer deposition process.

WO2007/106076, for example, describes a method of atomic layerdeposition wherein a substrate is mounted on a drum. This drum isrotated along a nozzle that supplies a precursor gas. In this way,multiple layer atomic layers can be deposited in a rather short time.However, the method of WO2007/106076 can only be applied on a substratethat has a length equal to or smaller than a circumference of the drum.In addition, the time necessary for mounting the substrate to the drummay at least partly or even completely undo the time gained by rotatingthe substrate rapidly along the nozzle.

Another R2R ALD process is described in WO2011/099858, and was developedby the present inventors. This document discloses a method of depositingan atomic layer on a substrate. The method comprises supplying aprecursor gas from a precursor-gas supply of a deposition head that maybe part of a rotatable drum. The precursor gas is provided from theprecursor-gas supply towards the substrate. The method further comprisesmoving the precursor-gas supply by rotating the deposition head alongthe substrate which in its turn is moved along the rotating drum.

The substrate is not confined in its length, as is the case inWO2007/106076, and is led to a movement path following the circumferenceof the deposition head such as to process the substrate surface.Although this provides an important advantage, the additional handlingsteps also expose the substrate to an increased risk of being damaged.Moreover, there is an ongoing objective to increase efficiency andcontrollability of the process, for example in terms of processing timeand energy consumption, as well as an objective to scale down theprocess in terms of the size thereof.

It is an object of the invention to provide a method of and apparatusfor depositing an atomic layer that at least partly meets one or more ofthe abovementioned objectives, and to diminish the problems of knownmethods.

Accordingly, the invention provides a method of performing atomic layerdeposition on a substrate by supplying a precursor gas towards thesubstrate using a deposition head comprising a precursor gas supply,having the precursor gas react near, e.g. on, a surface of the substrateso as to form an atomic layer moving the precursor-gas supply relativeto and along the substrate by rotating the deposition head whilesupplying the precursor gas; thus depositing a stack of atomic layerswhile continuously moving the precursor-gas supply in one direction,whereas the method is performed while keeping the surface of thesubstrate contactless with the output face by means of a gas bearing,and guiding the substrate at least one of to or from a movement pathdefined by an output face of the deposition head using a guiding unitfor bending the substrate having the surface of the substrate on anouter bend side, and pulling the substrate away from the output face byusing a pressure based pulling unit contiguous to the guiding unitopposite the output face.

As an improvement to the process, the present invention enables moreefficient use of the circumference of the deposition head to meet theobjectives defined above. In order to make use of a large part of thecircumference, the entrance and exit points of the substrate to and fromthe movement part are to be placed close to each other. Since thesubstrate is to be bent towards and away from the movement path onentrance and exit respectively, this also increases the chance ofcontact between the surface of the substrate and the deposition head. Inview however of the relative velocity between the substrate and thedeposition head, contact between the substrate and the deposition headis to be prevented such as to prevent damage to the substrate surface.

Although a guiding unit comprising capstans and possibly auxiliaryrollers are used to guide the substrate into the movement path past theoutput face, the additional pressure based pulling units of the presentinvention cause the substrate to align to the movement path earlier uponentrance (and longer upon exit). The risk of contact between thesubstrate and the deposition head is thereby reduced, which allows forthe entrance and exit points of the substrate to and from the movementpath to be brought closer to each other. This improvement thereforeincreases the length of the movement path past the output face, which isbeneficial to the process as explained above.

The increased length of the movement path allows more flexibility withrespect to a number of parameters of the design. For example, onlyincreasing the length of the movement path keeping other parametersunchanged increases the duration of the processing cycle in case thevelocity of the substrate and the rotation velocity of the depositionhead are unchanged. On the other hand, if the duration of the processcycle is kept constant, the velocity of the substrate may be increasedincrease making the process faster. The process thus becomes moreefficient. Alternatively or in addition, the radius of the depositionhead maybe decreased to thereby make the design of an apparatus forcarrying out the process to be more compact, decreasing its weight andsize. As indicated, the added flexibility may be used to benefit anumber of design parameters.

The substrate used in the process is flexible. Using a flexiblesubstrate combines well with the rotating deposition head. Such aflexible substrate allows for bending the substrate which facilitatesguiding the substrate around the rotating deposition head. The flexiblesubstrate is guided by leading the substrate across capstans, rollers orother means forming the guiding unit, which lie close to each other toallow for most efficient use of the circumference of the deposition headas defining the movement path. A guiding unit on entrance of thesubstrate, bends the substrate such that its direction of movementbecomes aligned with the movement path. On exit, a guiding unit inaccordance with the invention keeps the substrate aligned for as long aspossible, thereafter bending it away from the output face towards itsexit transport direction. The surface of the substrate, in order to facethe output face of the deposition head in the movement path, is on theouter bend side facing outward.

The guiding unit, by means of for example the capstans, allows tensionto be applied to the substrate for feeding and removing the substrate astightly as possible into and out of the entrance and exit point, to andfrom the movement path. The amount of tension applied is limited such asto prevent damage to the substrate or to the atomic layer deposited onthe substrate during the process. The additional pressure based pullingunits prevent the substrate to bend slightly towards the deposition headnear the guiding units, e.g. due to the applied tension beinginsufficient. As will be appreciated, any contact between the substrateand the deposition had is to be prevented since it may result inscratching of the substrate surface. The pressure based pulling unitallows to pull the substrate away from the output face of the depositionhead without handling the (processed or to be processed) surface of thesubstrate or even apply force it. Damage may thus be effectivelyprevented.

In accordance with a preferred embodiment of the invention, the step ofpulling is performed using a Bernoulli gripper for contactless pullingof the substrate. A Bernoulli gripper uses airflow to adhere to anobject without physical contact, relying on the Bernoulli airflowprinciple: the static pressure within an air flow is lower at higherflow velocities. A Bernoulli gripper creates a high velocity air flowparallel to the back side of the substrate, thereby creating a lowpressure area. This causes a net force on the substrate, pulling thesubstrate towards the gripper. At the same time, the gas flow created bythe Bernoulli gripper prevents contact between the substrate and thegripper.

In addition to the pressure based pulling unit, the process may furtheruse forced-flow gas inlets for creating an air flow near the outer bendside, for example towards the surface of the substrate or under an angleor parallel therewith, for forcing the surface of the substrate awayfrom the output face of the deposition head.

As described above, the process uses gas bearings for keeping thesubstrate surface contactless with the output face during the process,i.e. in the movement path around the circumference of the depositionhead. The gas bearings forms a gas-bearing layer that separates thesubstrate and the deposition head. In this way, a rather narrowseparation distance between the rotating deposition head and thesubstrate may be maintained. The separation distance may e.g. be at most200 micrometers, at most 100 micrometers, at most 15 micrometers, or atmost 10 micrometers, e.g. around 5 micrometers. At the same time, theseparation distance may be at least 3 micrometers, at least 5micrometers, or at least 10 micrometers. Such small separation distancesdecrease an amount of excess precursor gas that is provided towards thesubstrate. This may be worthwhile as the precursor gas usage may usuallyadd to production costs.

In accordance with a further embodiment, the gas bearings are createdusing the precursor gas. The precursor gas is a processing gas whichusually consists primarily of a bearer gas containing a fraction ofactive precursor gas component. It has been found that the precursor gascan be used perfectly well as bearing gas, in order to prevent local lowpressure areas causing local reduction of the distance between thesubstrate and the output face. This further prevents any contact betweenthe substrate and the output face of the deposition head duringprocessing.

In order to further control the process, a step of pre-heating of atleast one of the gas or the substrate is included in the process. Thisstep may be performed using a heater which is included in at least oneof: the deposition head, the one or more gas supplies, or the guidingunit.

In accordance with an embodiment, the method comprises moving thesubstrate relative to and along an, at least partly rounded,circumference of a rotatable drum that comprises the deposition head.The drum may comprise at least one gas flow channel for connecting theone or more gas supplies with a sealing piece that seals at least partof the drum's surface. The one or more gas supplies are provided withgas through the at least one gas flow channel via the sealing piecewhile rotating the drum relative to the sealing piece for providing thestep of moving of the precursor supply. Either the drum or the sealingpiece, or both, may comprise one or more gas outlets/inlets, where theother of the drum and/or sealing piece comprises one or morecircumferential grooves in its surface sealed by the drum. Duringrotation of the drum, for supplying the gas towards the substrate, thegas outlets/inlets lie opposite the sealed grooves, and a part of thegas flow path is formed by the sealed grooves.

The step of pre-heating, in the above case and in accordance with afurther embodiment, may be performed using an infrared radiation typeheating system, and wherein the drum is made of a material comprisinganodized, preferably opal-anodized, aluminum. Efficient infraredradiative heating devices may include for example (but not limitedthereto) tungsten-halogen lamps and SiC-based heaters. The emittedwavelength spectrum of such radiative heating devices is mainly in theinfrared part of the electromagnetic spectrum. The emissivity (thusabsorptivity) of aluminum and its alloys can be significantly increasedby oxidation. Thus, the infrared heaters combined with anodized oropal-anodized aluminum (having an absorption coefficient up to 0.9),form an effective internal drum heating system.

The translational velocity of the precursor-gas supply relative to thesubstrate may be constant in time or may be varied in time. Optionally,during depositing the atomic layer, the translational velocity of theprecursor-gas supply is larger than and/or is directed against atranslation velocity of the substrate. This further increases adeposition rate of the atomic layers. For example, an absolute value ofthe translational velocity of the precursor-gas supply can be at least 5times, at least 10 times, at least 20 times, at least 50 times, at least100 times, at least 500 times, at least 1000 times, at least 5000 times,and/or at least 10000 times larger than an absolute value of thetranslational velocity of the substrate. In an embodiment the substratemay be moved very slowly or held still while the precursor head movesalong the substrate surface thus depositing any desired number oflayers. It may be clear that optionally the translational velocity ofthe precursor-gas supply may be directed in a direction of thetranslational velocity of the substrate.

The output face may have a substantially rounded, typically asubstantially cylindrical or conical, e.g. frustoconical, shape and/orfrustum shape, defining a movement path of the substrate. Hence, theoutput face may have a substantially cylindrical, conical, or frustumshape. Such an output face combines well with a rotating precursor head,because it enables maintaining, in use, a rather constant separationdistance between the precursor head and the substrate.

It is noted that US 2007/0281089 A1 does not disclose a deposition headhaving an output face that: at least partly faces the substrate duringdepositing the atomic layer, is provided with the precursor-gas supply,and has a substantially rounded shape that defines a movement path ofthe substrate. It is further noted that US 2007/0281089 A1 does also notdisclose a precursor-gas supply that is shaped in elongated form along,or inclined to, an axial direction of the deposition head, and does alsonot disclose that the precursor-gas supply may extend, along a curvedoutput face, in a direction along or inclined with the axis of rotationof the deposition head. Instead, US 2007/0281089 A1 discloses anapparatus wherein an output face and a precursor-gas supply extendperpendicular to the axial direction and the axis of rotation. Thishinders homogeneous deposition on the substrate. For example, depositionclose to the axis of rotation will be different from deposition furtheraway from the axis of rotation. Furthermore, at the position of the axisof rotation no deposition is possible. As a result, in US 2007/0281089A1 the substrate is moved only over less than half of an area of anoutput face.

The method may comprise confining the precursor gas by means of a coverthat faces the deposition head outside locations where the substratefaces the deposition head. By means of the cover, flow of precursor gasto an outer environment of an apparatus with which the method can becarried out, may be substantially hindered or even prevented. The covermay extend along and/or in the gap between the first and second part ofthe substrate.

The inventor recognized that the features of this embodiment may beapplied more broadly, optionally in combination with one or more of theother embodiments and/or features described herein. In accordance with afurther aspect of the invention, there is provided an apparatus forperforming atomic layer deposition on a substrate, which apparatuscomprises a deposition head including one or more gas supplies, the oneor more gas supplies including a precursor gas supply for supplying aprecursor gas towards the substrate, wherein the one or more gassupplies are arranged on an output face of the deposition head, andwherein the output face has a substantially rounded shape defining amovement path for the substrate over at least part of the output face,such that in use the supplied precursor gas reacts near, e.g. on, asurface of the substrate facing the output face so as to form an atomiclayer on the substrate surface, the apparatus further comprising a mountfor rotatably mounting the deposition head; a driver arranged forrotating the deposition head so as to move the precursor gas supplyrelative to and along the substrate while supplying the precursor gas,for thereby depositing a stack of atomic layers while continuouslymoving the precursor-gas supply in one direction; and a gas bearingprovided by the one or more gas supplies for keeping the surface of thesubstrate contactless with the output face, and wherein the apparatusfurther comprises a guiding unit for guiding the substrate at least oneof to or from the movement path by bending the substrate having thesurface of the substrate on an outer bend side, and a pressure basedpulling unit contiguous to the guiding unit opposite the output face,for pulling the substrate away from the output face during said guidingfor preventing contact between the substrate surface and the output facenear the guiding unit.

In an embodiment of the invention, the pressure based pulling unit ofthe apparatus comprises a Bernoulli gripper for contactless pulling ofthe substrate.

In another embodiment, the apparatus further comprises a forced-flow gasinlet arranged near the outer bend side facing the surface of thesubstrate, for creating a gas flow for forcing the surface away from theoutput face.

In yet another embodiment, the apparatus comprises a rotatable drum thatcomprises the deposition head, wherein for providing gas to the gassupplies the drum comprises at least one gas flow channel connecting theone or more gas supplies with a sealing piece that seals at least partof the drum's surface, wherein the sealing piece is connectable to atleast one gas source, wherein one of the drum or sealing piece comprisesone or more gas outlets/inlets and the other of the drum or sealingpiece comprises one or more circumferential grooves in its surfacesealed by the drum, and wherein the one or more gas outlets/inlets andthe one or more circumferential grooves are arranged such that in use,during a rotation of the drum, the gas outlets/inlets lie opposite thesealed grooves over at least a part of a revolution of the rotating drumforming a part of a gas flow path between the gas source and the one ormore gas supplies.

In an embodiment, the apparatus comprises a heater which is included inat least one of: the mount, the deposition head, the one or moresupplies, the guiding unit, or in embodiments where any of the followingare present: the drum, at least one gas flow channel, at least one ofthe gas outlets/inlets, or at least one circumferential groove.

In an embodiment, the apparatus comprises a rotatable drum thatcomprises the deposition head, wherein the drum is made of a materialcomprising anodized, preferably opal-anodized, aluminum, said apparatusfurther comprising an infrared radiation type heating system.

Other advantageous embodiments of the apparatus and method are describedin the dependent claims.

The invention will now be described, in a non-limiting way, withreference to the accompanying drawings, in which:

FIG. 1 shows an apparatus for depositing an atomic layer on a substrate,in a first embodiment according to the invention;

FIG. 1A shows an example of a stack of layers with offset;

FIG. 1B shows an example of isolated stacks of layers;

FIG. 1C shows a schematic cross section wherein a deposition head, aprecursor-gas supply and optionally a drum are movable with respect toan axle;

FIG. 1D shows a schematic cross section of an embodiment comprising agas transition structure.

FIG. 1E(A) shows a schematic cross section of another embodimentcomprising a gas transition structure.

FIG. 1E(B) shows a side view of FIG. 1E(A).

FIG. 1E(C) shows a zoom of FIG. 1E(B).

FIG. 1F shows a schematic cross section of yet another gas transitionstructure.

FIG. 2A schematically shows a basic functional part of a deposition headof the apparatus 2 in the first embodiment, and a substrate;

FIG. 2B partly shows a possible structure of a part of the depositionhead shown in FIG. 2A;

FIGS. 3A and 3B show a part of a transporter;

FIG. 4 shows an apparatus 2 for depositing an atomic layer on asubstrate 4, in a second embodiment according to the invention;

FIG. 4A shows an example of an output face provided with elongatedlyshaped supplies;

FIGS. 5 and 6 show variations of the apparatus 2 in the secondembodiment, wherein the deposition head is provided with a cavity that,in use, faces a substrate;

FIG. 6A shows a variation of the deposition head in the secondembodiment;

FIG. 7 shows an apparatus in a third embodiment according to theinvention, in assembly with a substrate;

FIG. 8 shows an apparatus in a fourth embodiment according to theinvention, in assembly with a substrate;

FIG. 9 schematically shows a moving direction of a substrate and amoving direction of a deposition head;

FIG. 9A shows an embodiment of a deposition head of an apparatusaccording to the invention, wherein a precursor-gas supply extends alonga helical path;

FIG. 9B shows a part of a cross-section A-A′ as indicated in FIG. 9A;

FIG. 10 shows a stack of layers and shows subsequent back-turningpositions;

FIG. 11A shows an example wherein an axis of rotation of a depositionhead is aligned with a moving direction of a substrate; and

FIG. 11B shows the deposition head in a viewing direction along the axisof rotation of the deposition head.

FIG. 12 shows a schematic cross section of an embodiment comprising agas switching structure.

FIG. 13 shows a schematic cross section of an embodiment comprisinganother gas switching structure.

FIG. 14 shows yet another gas switching structure.

FIG. 15 shows an embodiment with yet another gas switching structure.

FIG. 16 shows a detail of the gas switching structure of FIG. 15.

FIG. 17 shows an embodiment of the gas switching structure of FIG. 15.

FIG. 18 shows another embodiment of the gas switching structure of FIG.15.

FIG. 19 schematically illustrates a guiding structure for guiding asubstrate to and from the movement path following the circumference of adeposition head in an apparatus and method of the present invention;

FIG. 20 schematically illustrates the principle of a Bernoulli gripper;

FIG. 21 schematically illustrates a heating arrangement in an apparatusand method of the present invention.

Unless stated otherwise, like reference numerals refer to like elementsthroughout the drawings.

Atomic layer deposition is known as a method for depositing a monolayerof target material in at least two process steps, i.e. half-cycles. Afirst one of these self-limiting process steps comprises application ofa precursor gas on the substrate surface. A second one of theseself-limiting process steps comprises reaction of the precursor materialin order to form the monolayer of target material on a substrate. Theprecursor gas can for example contain metal halide vapours, such ashafnium tetra chloride (HfCl₄), but can alternatively also containanother type of precursor material such as metalorganic vapours, forexample tetrakis-(ethyl-methyl-amino) hafnium or trimethylaluminium(Al(CH₃)₃). The precursor gas can be injected together with a carriergas, such as nitrogen gas, argon gas or hydrogen gas or mixturesthereof. A concentration of the precursor gas in the carrier gas maytypically be in a range from 0.01 to 1 volume %, but can also be outsidethat range.

Reaction of the precursor gas may be carried out in a number of ways.First, a monolayer of deposited precursor material can be exposed to aplasma. Such plasma-enhanced atomic layer deposition is especiallysuitable for deposition of medium-k aluminum oxide (Al₂O₃) layers ofhigh quality, for example for manufacturing semiconductor products suchas chips and solar cells. Thus, the invention may e.g. be used formanufacturing solar cells, in particular for manufacturing flexiblesolar cells, by depositing one or more layers of a solar cell. Second, areactant gas can be supplied towards the deposited monolayer ofdeposited precursor material. The reactant gas contains for example anoxidizing agent such as oxygen (O₂), ozone (O₃), and/or water (H₂O).Nitriding agents such as N₂, NH₃, etc. can be used alternatively to formnitrides such as silicon nitride (Si₃N₄). It is noted that the reactantgas may also be considered as a (second) precursor gas, e.g. two or moreprecursor gasses may react with each other to form an atomic layer as areaction product.

In an example of a process of atomic layer deposition, various stagescan be identified. In a first stage, the substrate surface is exposed tothe precursor gas, for example hafnium tetrachloride. Deposition of theprecursor gas is automatically terminated upon saturation of thesubstrate surface with a monolayer of by a single layer of chemisorbedprecursor gas molecules. This self-limitation is a characteristicfeature of the method of atomic layer deposition. In a second stage,excess precursor gas is purged using a purge gas and/or a vacuum. Inthis way, excess precursor molecules can be removed. The purge gas ispreferably inert with respect to the precursor gas. In a third stage,the precursor molecules are exposed to a plasma or to a reactant gas,for example an oxidant, such as water vapor (H₂O). By reaction offunctional ligands of the reactant with the remaining functional ligandsof the chemisorbed precursor molecules, the atomic layer can be formed,for example hafnium oxide (HfO₂). In a fourth stage, excess reactantmolecules are removed by purging. In addition, additional reactantstimulation systems may be used, for example, thermal, photonic orplasma excitation.

FIG. 1 shows an apparatus 2 for depositing an atomic layer on a, e.g.flexible, substrate 4, in a first embodiment according to the invention.The apparatus 2 comprises a deposition head 6 having precursor-gassupply 8. The deposition head 6 may be comprised by a rotatable drum 5.The drum 5 may comprise a rotatable wheel 5′ with the deposition head 6attached thereto. By means of the precursor-gas supply, precursor gascan be supplied towards the substrate 4. The apparatus 2 furthercomprises a mount arranged for rotating the precursor-gas supply alongthe substrate 4. The mount may comprise a bearing 12 that is arranged toreceive an axle 10. The axle may be rigidly connected to theprecursor-gas supply. Through the bearing 12, the axle 10 and thedeposition head 6 can rotate with respect to the mount. An axis ofrotation around which the deposition head can rotate may coincide with acenter of the axle 10, e.g. with a length axis of the axle 10. The mountmay thus be adapted for realizing a translational velocity of theprecursor-gas supply along the substrate.

Alternatively, other mounting embodiments may be applied that do notcomprise axle 10 or bearing 12. In particular, the drum may be mountedvia output face 26. Hence, it may, more in general, be clear that theaxis of rotation of the deposition head may coincide with an axis ofrotation of the drum.

The apparatus 2 may further comprise a driver that is connected to theaxle 10 for driving the axle 10 and the deposition head. The driver maybe provided with a driving controller 9A. By means of the drivingcontroller, the driver may be adapted for realizing and controlling atranslational velocity of the precursor-gas supply along the substrate.Such drivers and driver controllers are known as such so that a furtherdescription is deemed superfluous.

The axle 10 may comprise an elongated cavity aligned along its axis. Inuse, the precursor gas may be transported through the cavity 11A (e.g.see FIG. 1C) of the axle. Thereto a gas supply structure may extend intothe cavity of the axle. From the cavity 11A of the axle 10, theprecursor gas may be transported to the precursor-gas supply.

Ways to obtain a gas-tight connection between the gas supply structureand the axle that allows for rotational motion between the axle and thegas supply structure are discussed in more detail in the following e.g.with reference to FIGS. 1C-1F and FIGS. 15-18.

A few general requirements for a gas supply system onto a rotatingspatial reel-to-reel (R2R) atomic layer deposition (ALD) system may bethat if the gas supply originates from a stationary feed assembly, for amoving, i.e. rotating, spatial ALD system, a gas feed-through design isneeded to feeding the gas from the stationary feed assembly to therotating ALD system. Such feed-through should not generate particlesthat would inevitably contaminate the ALD process, resulting in, e.g.,the creation of pinholes in deposited barrier layers. Thus preferablythe two vapor supplies (e.g. a precursor gas TMA and a reactant gas H₂O)are completely separated throughout the entire gas circuit systems ofthe R2R equipment.

In the following, three main designs are described for two or moreindependent, separated gas supply configurations:

In a first design there is provided a coaxial drum set with internal gasbearing/concentric tubes with leaky seals, and switchable flowinterruption valves. One is a gas supply design where the supply line ofone precursor gas is closed when its gas inlet opening is moving intothe segment where the drum is not covered by the foil. This can beaccomplished by inserting a valve system that can be e.g. magnetically,electrostatically and/or gravitationally actuated or a combinationthereof, described later in more detail with reference to FIG. 14.Several precursors and process gases may run through different innertubes of a (concentric) tube assembly. Separation of precursors andother process gases can be done by pressure differences. For example,inert gas (used for purging) is allowed to flow in the precursor tube,but not the other way around. (Concentric) tubes with leaky seals allowfor gas and precursor supply from one or both sides of the drum. E.g.FIG. 1E illustrates this concept.

In a second design there is provided an integrated multiple flowselector/restrictor system, built in a coaxial drum set withgas-bearings and gas feed-through from a so-called shape-controlledaxis. Here, the gas feed-through can be equipped with a gas bearing. The(inert) gas bearing may separate the rotating tube from the stationarytube; the gas bearing may be leaky. The concept of concentric tubes withleaky seals can be augmented by gas bearings to decrease leakage. E.g.FIG. 1F illustrates this concept. The supply design may be based onintegrated flow restrictor supply line circuits, one circuit for eachreactant and gas bearing of the flexible substrate. The off-and-onswitching of gases is based on supply lines that are composed bygrooves, engraved in the circumference of a rotating drum and insertsaround the rotating drum. The inserts form two halves of a concave crosssection to compose a divider chamber when mounted face-to-face, and onthe drum.

In a third design there is provided an integrated multiple flowselector/restrictor system, built in a drum with gas feed-through fromone or two disk(s) sealingly held against the axial side(s) of the drum.This supply design is based on integrated flow restrictor supply linecircuits, one circuit for each precursor and/or reactant gas and one forthe gas bearing of the flexible substrate. The off-and-on switching ofgases is based on supply lines that communicate upon rotation of theouter disk(s) with respect to the inner drum. The rotating ALD drum canhave a gas bearing. The gases are supplied to the stationary part of thegas bearing. The gases are transferred from the stationary part to therotating part through internal channels in the stationary and rotatingpart. Multiple channels with different gases/precursors can be used inparallel using gas separation. FIG. 17 or 18 illustrate an example.

FIG. 1C shows an embodiment wherein the deposition head, theprecursor-gas supply, and optionally the drum 5 are movable with respectto the axle 10. A mount of the apparatus may comprise the axle 10. FIG.1C shows a schematic cross-section of the axle 10 provided with a first,e.g. elongated, axle cavity 11A for supplying the precursor gas throughthe axle towards the precursor-gas supply.

In the cross-section of FIG. 1C, the deposition head 6 and the substrate4 are visible at only one side of the cross-section. However, in anembodiment, other cross-sections may be possible wherein the depositionhead 6 and/or the substrate 4 is visible at two sides of thecross-section. The axle 10 may be provided with a second, e.g.elongated, axle cavity 11B for supplying an additional gas through theaxle towards the deposition head. For example, the second axle cavity11B may be arranged for supplying a reactant gas through the axletowards a reactant-gas supply 42. Alternatively, the second axle cavity11B may be arranged for supplying a purge gas through the axle towards apurge-gas supply 38 (e.g. see FIG. 1E).

The axle cavities 11A, 11B may be comprised by an axle feed-through 111for supplying at least the precursor gas through the axle towards theprecursor supply. Advantageously, an axle gas bearing 19 may be providedin between the axle on one hand and the drum and/or the deposition headon the other hand. A bearing pressure in the axle gas bearing may becontrolled to substantially prevent leakage out of the axle cavities11A, 11B. Such an axle gas bearing may decrease the amount of particlesthat is generated during rotation, compared to e.g. sliding mechanicalcontact between the axle and the drum or between the gas supplystructure and the axle. The axle gas bearing 19 may provide for a gasconnection between the axle on one hand and the rotating drum and/or thedeposition head on the other hand that substantially prevents leakage ofprecursor gas through the axle gas bearing.

Thus, the mount may be provided with a mount gas bearing, e.g. the axlegas bearing, that forms part of an enclosure of a gas connection betweena gas supply and/or drain structure (not drawn but e.g. conventional) onone hand, and the deposition head on the other hand. A pressure in saidmount gas bearing may be arranged for preventing leakage of precursorgas through the mount gas bearing out of the gas connection. At thesame, the mount gas bearing may be arranged for allowing rotation of thedeposition head with respect to the gas supply and/or drain. Rotation ofthe deposition head 6 and the precursor-gas supply 8, and optionally ofthe drum 5, is indicated with arrow 21. In such an embodiment, the axlemay in use be stationary. Then, the axle may be rigidly connected to thegas supply structure.

Additionally, or alternatively, the apparatus may in an embodiment beprovided with a cartridge that contains the precursor gas. Then, thegas-tight connection may be omitted. Transport of other gasses can beanalogous to the transport of the precursor gas towards the precursorgas supply as described hereinbefore.

Thus, more in general, the mount may comprise an axle for, optionallyrotatably or rigidly, mounting the deposition head and/or the drumthereon. The axle may be provided with an axle feed-through, e.g. anaxle cavity, for supplying at least the precursor gas through the axletowards the precursor-gas supply. A method according to the inventionmay comprise: providing the deposition head and/or the drum mounted onan axle; providing at least the precursor gas through the axle towardsthe precursor-gas supply. The mount may be provided with a mount gasbearing that forms part of an enclosure of a gas connection between agas supply and/or drain structure on one hand, and the deposition headon the other hand. A pressure in said mount gas bearing may be arrangedfor preventing leakage of gas through the mount gas bearing out of thegas connection. The mount gas bearing may be arranged for allowingrotation of the deposition head with respect to the gas supply and/ordrain. The apparatus 2 may comprise a transporter system to transportthe substrate along the precursor-gas supply. The transporter maycomprise a closure element or guide 15 for transporting the substrate 4along the precursor-gas supply 8 and deposition head 6, as furtherillustrated in FIGS. 3A and 3B. Furthermore, such a transporter, e.g.such a guide, may comprise capstans 14. The capstans may be stationary.However, preferably, the capstans are rolling capstans, i.e. capstansthat can be rotated around an axis of symmetry or a length axis of thecapstans 14. The transporter may further comprise a transportationcontroller 9B for controlling a velocity with which the substrate 4passes the rolling capstans 14. Such a transportation controller 9B isknown as such so that a further description is deemed superfluous. Thetransportation controller may for example control a rotation velocity ofone or both of the rolling capstans 14. Thereto the transportationcontroller 9B may be connected to the rolling capstans 14.

Thus, by means of the transportation controller 9B and the drivingcontroller 9A, respectively, a translational velocity of the substrateand the translational velocity of the precursor-gas supply can becontrolled. Preferably, the translational velocity of the precursor-gassupply is larger than the translational velocity of the substrate. Inthis way, relative movement between the precursor-gas supply and thesubstrate with a relatively high velocity can be obtained.

The translational velocity of the substrate may e.g. be approximately0.01-0.2 m/s. For all embodiments presented herein, the precursor headmay rotate with a frequency of at least 0.1 or 1 revolution per second.The precursor head may rotate with a frequency of e.g. approximately 50revolutions per second. The translational velocity of the precursor-gassupply may e.g. be approximately 1 m/s. As will be appreciated, this isdependent on the geometry of the set-up. Furthermore, as theprecursor-gas supply in use rotates, the precursor-gas supply can movein a continuous fashion in the same direction along one and the samepart of the substrate 4 a plurality of times. In this way, a pluralityof atomic layers can be deposited on the substrate. In this way onerelatively thick composite layer can be obtained that comprises aplurality of atomic layers that may mutually overlap. Hence, more ingeneral, the precursor-gas supply may rotate continuously in the samedirection, along one and the same part of the substrate a plurality oftimes, for obtaining a composite layer that comprises a plurality ofatomic layers that mutually overlap. Hence, it may be clear that termslike ‘rotate(s)’ and ‘rotating’ used herein may mean e.g. ‘revolve(s)’,respectively, revolving′, ‘gyrate(s)’, respectively, ‘gyrating’, or‘spin(s)’, respectively, ‘spinning’. Hence, an apparatus according tothe invention may be arranged for rotating the precursor-gas supplycontinuously in the same direction, along one and the same part of thesubstrate a plurality of times, for obtaining a composite layer thatcomprises a plurality of atomic layers that mutually overlap.

The velocity of relative movement can even be increased if thetranslational velocity of the precursor-gas supply is directed against atranslational velocity of the substrate.

In a variation, the transportation controller and the driving controllerare arranged for moving the substrate simultaneously with supplying theprecursor gas towards the substrate. In this way, an offset may berealized between subsequently deposited atomic layers. In this way, aseam between edges of atomic layers that extends perpendicularly to thesubstrate can substantially be prevented. FIG. 1A shows an example of astack of atomic layers 92.i (i=n, n+1, . . . ) with offset 93 depositedin this way.

The offset 93 may, more in general, depend on the translational velocityof the precursor-gas supply and of the substrate. It may e.g. be clearthat, if the precursor-gas supply 8 and the substrate 4 move in the samedirection and the translational velocity of the precursor-gas supply islarger than the translational velocity of the substrate 4, the offset 93may then decrease if the translational velocity of the precursor-gassupply 8 increases.

In another variation, the transportation controller and the drivingcontroller are arranged for moving the substrate subsequently tosupplying the precursor gas towards the substrate. In that case, thesubstrate is not moved when supplying the precursor gas towards thesubstrate. When a stack of layers is deposited in this way, supplyingthe precursor gas towards the substrate may be stopped when moving thesubstrate. In this way, an isolated stack of layers may be deposited onthe substrate 4. FIG. 1B shows an example of isolated stacks 92 oflayers 92.i (i=n, n+1, . . . ) deposited in this way. The stack 92 maytypically comprise approximately a hundred to a thousand atomic layers,three of which are drawn in FIG. 1B.

The apparatus 2 may further comprise a cover 16. By means of the cover,the precursor gas can be substantially enclosed or confined. The cover16 faces part of the deposition head and/or the rotatable drum 5 andextends between parts of the substrate 4, in this example parts of thesubstrate that are in mechanical contact with the capstans 14. With theinsertion of cover 16, precursor gas can be substantially enclosed orconfined to a space 18 bounded by the deposition head, the substrate 4,and the cover 16. In the space 18, a gas bearing may be created by gasinjected from the precursor head, as will later be explained withreference to FIGS. 4-6. Without the cover 16, precursor gas may leakaway towards an outer environment 20 of the apparatus 2. This may resultin unwanted contamination and particles formed on the substrate.

FIG. 1D shows a schematic cross section of an embodiment of theapparatus 2 comprising a drum 5 that is rotatable around an axle 10 withgas bearings 19. In use, the precursor gas may be transported throughthe cavity 11A of the axle 10 to provide the precursor gas supply 8 tothe substrate 4. The drum 5 may revolve or rotate around the axle 10 ina rotation trajectory 62 while the precursor gas from the precursor gassupply 8 is deposited on the substrate 4 by the deposition head 6 thatis comprised in the drum 5. The deposition head 6 may comprise aprecursor gas supply 8, and e.g. a narrow slit, in gas contact with theprecursor gas supply 8, extending along the surface of the drum 5, e.g.in an axial direction.

To provide the precursor gas from the stationary axle 10 to therevolving drum 5, a gas transition structure 510 is provided. This gastransition structure 510 may comprise e.g. a combination of one or moregas outlets in the axle 10 that are connected to the axle feed-through111 and one or more corresponding circumferential grooves 57 in therotatable drum 5. At positions along the rotational trajectory 62 of thedrum where the grooves 57 lie opposite the gas outlet, e.g. along therotation trajectory of the drum, gas may flow between the stationaryaxle 10 and the rotating drum 5. At positions along the rotationaltrajectory 62 where the groove is absent or does not lie opposite thegas outlet, the flow of gas may be interrupted or substantially loweredby the surface of the drum that seals the gas outlet.

The term “circumferential grooves” as used herein refers to the factthat the grooves follow a circular path e.g. with a fixed radius that atleast partly follows a rotation of a gas inlet or outlet in the drum.The grooves may be semi-circumferential e.g. be interrupted along thecircumferential trajectory. While in the current figure thecircumferential grooves are on an inner surface of a drum, the groovesmay also be on an outer surface of the drum or the axle or,alternatively, the grooves may be on an axial side of the drum, e.g. ina surface of a seal plate held sealingly to a side of the drum (see e.g.FIGS. 15-18).

Alternatively, instead of the drum 5 comprising a groove and the axle 10a gas outlet, the drum 5 may comprise a gas inlet and the axle 10 maycomprise grooves connected to the axle feed-through 111. Alternativelystill, both the axle 10 and the drum 5 may comprise circumferentialgrooves or they may both comprise one or more gas inlets/outlets thatare opposite each other during parts of the rotational trajectory 62.Also any other combination of grooves and outlets is possible, e.g. thedrum 5 may have grooves that lie opposite gas outlets of the axle 10 aswell as the drum 5 having gas inlets that lie opposite grooves in theaxle 5. The grooves in the drum 5 or axle 10 may be partly sealed by thesurface of the opposing structure, i.e. the axle 10 or drum 5,respectively. These sealed grooves may form channels that function aspart of a gas flow path between a gas source connected to the axlecavity 11A and the gas supply 8 that extends in the deposition head 6.The axle 10 may thus act as a sealing piece that seals the gas flow paththrough the grooves between the sealing piece (axle 10) and the drum 5.

To further improve sealing between the drum 5 and the sealing pieceformed by the axle 10, the gas bearings 19 may comprise a purge gassupply for providing a purge or bearing gas (e.g. nitrogen gas, N₂) thatmay provide both a smooth bearing function and a gas curtain between thetransition 510 and the external surrounding. The gas curtain may preventprecursor gas from escaping between an opening of the relativelyrotating parts of the drum 5 and axle 10. The gas bearing 19 may also beprovided with gas drains for draining both the purge gas and theprecursor gas. Preferably, the gas bearings 19 comprise grooves thatextend along the whole inner circumference of the drum 5 for preventingthe precursor gas from escaping the apparatus 2. A pressure of the purgegas is preferably higher than a pressure of the precursor gas. This waythe purge gas will flow from the gas bearings 19 towards the precursorgas supply 8 and not the other way around.

Additional gas bearings or purge gas outlets/inlets (not shown here) maybe provided between the substrate 4 and the drum 5 for providing asmooth relative movement of the drum 5 and substrate 4 as well aspreventing precursor gas from escaping from between the substrate 4 andthe drum 5. These additional gas bearings or gas curtains arepreferentially provided at the edges of the substrate 4 or depositionhead 6. Preferentially, the precursor gas supply and the drains arecomprised in a recess or cavity in the deposition head. A concentrationof precursor gas in the cavity that is to be deposited on the substratemay be controlled by controlling the pressure of the precursor gassupply and the (suction) pressure of the precursor-gas drains.

Accordingly, an advantageous method may comprise supplying the bearinggas from a bearing-gas supply of the deposition head towards thesubstrate for providing the gas-bearing layer, and supplying theprecursor gas by means of the precursor-gas supply in a cavity that isdefined in the deposition head and is facing the substrate, and drainingthe precursor gas by means of a precursor-gas drain of the depositionhead from the cavity for substantially preventing precursor gas toescape from the cavity, the method further comprising supplying thebearing gas by means of the bearing-gas supply at a distance from thecavity.

FIGS. 1E(A)-1E(C) show three views of a rotatable drum 5 with an axlecomprising concentric tubes 10 a and 10 b.

In FIG. 1E(A) a cross-section of a frontal view of the apparatus 2 isshown wherein along the rotational axis of the drum 5, there is providedan inner tube 10 a with a precursor gas 108 surrounded by an outerconcentric tube 10 b with a purge gas 138. The inner tube 10 a suppliesprecursor gas 108 via a radially extending axle feed-through 111 a to aprecursor gas supplies 8. The outer tube 10 b supplies purging gas 138via a radially extending axle feed through 111 b to purge gas supplies38. The gas supplies 8 and 38 are comprised in the rotating drum 5. Thesupplies may deposit gas onto a substrate 4 that partially covers thedrum. On positions where the substrate does not cover the drum 5, anouter cover 16 may be provided to prevent precursor gasses from escapingthe apparatus. On other positions where the substrate 4 follows thecircumference of the drum, a guiding structure 15 may be provided todefine the substrate path around the drum.

FIG. 1E(B) illustrates how the concentric tubes 10 a and 10 b, rotatingalong trajectory 62, may be provided with precursor gas 108 and purgegas 138 from stationary (non-rotating) gas sources 108′ and 138′,respectively. In particular, a gas transition structure 510 is providedwherein the rotating inner tube 10 a receives precursor gas 108 from astationary tube 10 a′ that connects to the precursor gas source 108′.Likewise, the rotating outer tube 10 b protrudes into a stationary tube10 b′ connected to the stationary purge gas supply 138 and receivespurge gas there from. Alternative to the shown embodiment, also thepurge gas supply may be provided through a combination of a rotatingtube sealed by a stationary tube.

In FIG. 1E(C) a zoom-in view is shown of the gas transition structure510 of FIG. 1E(B). The gas transition structure comprises connections ofthe inner tubes 10 a and 10 a′ that rotate with respect to each other.E.g. tube 10 a, connected to the rotating drum, may rotate while tube 10a′, connected to the gas source 108′, is held stationary.Preferentially, the purge gas 138 is provided with a higher pressurethan the precursor gas 108 such that the precursor gas 108 does notescape the leaky seals or opening 115 a between the rotating parts 10 aand 10 b.

Accordingly in an advantageous embodiment a gas supply 8 or 38 iscomprised in a drum 5 that receives gas 108 or 138 from a stationary gassource 108′ or 138′ via a gas flow path comprising relative rotatingparts 10 a and 10 a′ wherein a leakage of the precursor gas through anopening 115 between the relative moving parts 10 a and 10 a′ isprevented by a purge gas 138 provided around said opening having ahigher pressure than the precursor gas 108. In a further advantageousembodiment the relative rotating parts comprise two or more concentrictubes 10 a, 10 b wherein the precursor gas 108 is fed through an innertube 10 a and the purge gas 138 is fed through an outer tube 10 b.Alternatively to the concentric tubes, e.g. the gas bearings of FIG. 1Dmay provide the purge gas at a higher pressure than the precursor gasfor preventing a leakage of the precursor gas.

It is to be appreciated that while in the current figure two concentrictubes 10 a, 10 b are shown for supplying the precursor and purge gasses,additional concentric tubes may be provided, e.g. to drain the gasses.E.g. such a drain may have a lower pressure than both the precursor gasand purge gas be provided in a tube within the currently shown innertube. Alternatively, the tube may be provided concentrically around theouter tube, e.g. at a pressure below atmospheric pressure, such that anyleaky seals of the drain will not leak the gas to the externalsurrounding but instead will suck atmospheric gasses into the draintube. Additionally or alternatively, any number of concentric tubes maybe provided, e.g. in an alternating pressure arrangement wherein purgegas tubes are provided with a high pressure between two or moreprecursor gasses. It is noted that for the current embodiment the tubesneed only be concentric at the position where the parts rotate withrespect to each other, i.e. the gas transition structure 510. E.g. overa part of the axle the concentric tubes may connect to an arrangement ofparallel tubes.

It is noted that also the outer tubes 10 b and 10 b′ may rotate withrespect to each other. Escape of the (inert) purge gas 138 to theexternal surroundings may occur through opening 115 b between the tube10 b that may be rotating with respect to the stationary tube 10 b′connected to the purge gas supply.

FIG. 1F shows a schematic cross section of two connecting concentric gastubes for transporting a precursor gas 108. The inner tube may e.g. forman axle 10 of a rotating drum and is rotatable with respect to the outertube that may form a bearing 12 for holding the axle 10. The gastransition structure 510 may thus be formed between the relativelyrotating parts of the axle 10 and bearing 12. A leakage of the precursorgas 108 through an opening 115 between the relative moving parts 10 and12 is prevented by a purge gas provided around said opening by the gasbearings 19. Preferably the purge gas has a higher pressure than theprecursor gas 108. In this way the gas bearing or purge gas will flow indirection 113 into the tube or bearing 12 preventing the flow ofprecursor gas to the external surroundings, e.g. in direction 112.

FIG. 2A schematically shows a basic functional part of the depositionhead 6 of the apparatus 2 in the first embodiment, and the substrate 4.FIG. 2A illustrates how, along an output face 26 of the precursor head6, gasses may be supplied and drained. In FIG. 2A, arrow 28.1 indicatessupply of the precursor gas. Arrow 28.2 indicates draining of theprecursor gas and purge gas supplied by 30.1. Arrow 30.1 indicatessupply of the purge gas. Arrow 30.2 indicates draining of the purge gasand precursor/reactant gas supplied by 32.1. Arrow 32.1 indicates supplyof the reactant gas. Arrow 32.2 indicates draining of the reactant gasand purge gas supplied by neighboring 30.1. The supply of purge gas inbetween location of supply of active gasses, e.g. the reactant gas andthe precursor gas, in use spatially divides the active gasses. The basicfunctional part shown in FIG. 2 A may be repeated along thecircumference of the rotatable drum 5. Hence, more in general, theprecursor-gas supply is located, and preferably repeated, along thecircumference of the rotatable drum and/or along the circumference ofthe output face.

FIG. 2B partly shows a possible structure of the part of the depositionhead shown in FIG. 2A. FIG. 2B shows the precursor-gas supply 8, whichcan be used for a first reaction half-cycle. FIG. 2B further shows thatthe deposition head may have a precursor-gas drain 36 for draining ofthe precursor gas. The deposition head 6 may further have a purge-gassupply 38 and a purge-gas drain 40, for respectively supplying the purgegas towards the substrate and draining the purge gas away from thesubstrate. The deposition head may further have a reactant-gas supply 42for supplying the reactant gas towards the substrate 4, which can beused for the second reaction half-cycle. The reactant gas supplyfunctions as a means to have the precursor-gas react near, e.g. on, thesubstrate so as to complete the formation of an atomic layer. It may beclear that in this way the purge gas is supplied in between the reactantgas and the precursor gas in order to spatially divide zones associatedwith respectively the reactant gas and the precursor gas. This mayprevent reaction of the purge gas and the reaction gas at positionsother than on the substrate 4. In addition, or alternatively, otherreactant systems may be used, for example, thermal, photonic or plasmaexcitation.

More in general, gas supplies, e.g. the precursor-gas supply, thereactant-gas supply, and the purge-gas supply may be spaced apart fromeach other and from gas drains, e.g. the precursor-gas drain, thereactant-gas drain, and the purge-gas drain, by a separation length 43.

FIGS. 3A and 3B show a part of the transporter 17. FIGS. 3A and 3B showthe guide 15 comprised by the transporter. In use, the precursor-gassupply may rotate inside a central space 49 that may be enclosed by theguide 15. The guide 15 may have a mesh 48 attached to an inner lining ofthe guide or closure element 15. The transporter may further comprise acarrier 50 for attaching the substrate 4 thereto by means of pressure.The carrier 50 may comprise a mesh. Thereto the transporter may comprisea vacuum port 52 for creating a vacuum between the substrate 4 and thecarrier 50. Arrow 54 indicates how gas can be sucked away through thevacuum port 52 to attach the substrate 4 to the carrier 50. In use, thecarrier can be moved around the guide 15, along a transportation face 56of the guide 15 that is conformal with the output face 26. Other methodsof attaching the substrate to the carrier 50 are possible as well.

FIG. 4 shows an apparatus 2 for depositing an atomic layer on asubstrate 4, in a second embodiment according to the invention. FIG. 4shows the deposition head 6 and the cover 16 of the apparatus 2. Amoving direction of the substrate 4 is indicated by arrows 60. Arotating direction of the deposition head, and a moving direction of theprecursor-gas supply along the substrate, is indicated by arrow 62. Itmay thus be clear that in this example the translational velocity of theprecursor-gas supply is directed in a direction of the translationalvelocity of the substrate. If, for example, the substrate would move inthe direction of arrow 64, the translational velocity of theprecursor-gas supply along the substrate would be directed against thetranslational velocity of the substrate.

The apparatus 2 in the second embodiment further shows the output face26 of the deposition head 6. In FIG. 4, the output face in use faces apart of the substrate 4. In FIG. 4, the output face faces substantiallyeither the substrate 4 or the cover 16. The output face 26 may have asubstantially cylindrical shape. It may be clear that in this examplethe output face 26 defines a movement path of the substrate, as in usethe output face is separated from the substrate by a separation distanceD (see also FIG. 2A). It may further be clear that the output face 26 inthis example is substantially rounded along the entire circumference ofthe output face 26 around the axis of rotation of the deposition head.In other examples however, the output face 26 may e.g. be flat over partof the circumference of the output face 26 around the axis of rotationof the deposition head. Hence, more in general, the output face may besubstantially rounded along at least part of the circumference of theoutput face around the axis of rotation of the deposition head and/oraround the axis of rotation of the drum.

The output face 26 may be provided with the precursor-gas supply 8, inthis example with a plurality of precursor-gas supplies 8. The outputface 26 may further be provided with the precursor-gas drain 36, in thisexample with a plurality of precursor-gas drains 36. The output face 26may further be provided with the purge-gas supply 38, in this examplewith a plurality of precursor-gas supplies 38. The output face 26 mayfurther be provided with the purge-gas drain 40, in the example with aplurality of purge-gas drain 40. The output face 26 may further beprovided with the reactant-gas supply 42, in this example with aplurality of reactant-gas supplies 42. The output face 26 may further beprovided with a reactant-gas drain 68, in this example with a pluralityof reactant-gas drains 68.

There are, in this example, three groupings of gas supplies, and twogroupings of drains. Each precursor gas supply grouping has acorresponding drain grouping, which may also drain the surrounding purgegas. It may not be necessary to provide a separate drains for purge gassince the purge gas does not react with the precursor gasses.Optionally, there may also be provided more than two precursors gassupply groupings, in which case there are preferably enoughcorresponding drain groupings to keep those (pairs of) precursor gassesthat may react with each other separated. The number of drain groupings)is preferably at least equal the number of precursor groupings.Generally, the drain grouping for each precursor is kept separate fromall other groupings to prevent CVD (chemical vapor deposition) reactionsin the apparatus, which can result in particle generation or evenblockage of gas channels.

The gas supplies 8, 38, 42 and/or the gas drains 36, 40, 68 may beelongatedly shaped, i.e. shaped in elongated form, in an axial directionof the deposition head 6 and the drum 5. An array of gas supplies, e.g.precursor-gas supplies, may be regarded as a gas supply, e.g. aprecursor-gas supply, being shaped in elongated form. In general, theaxial direction may be aligned with, or coincide with, the axis ofrotation of the deposition head. Hence, it may, more in general, beclear that the axis of rotation of the deposition head may coincide withan axis of rotation of the drum.

FIG. 4A shows an example of the output face provided with theelongatedly shaped supplies. The axial direction 65 may be directedalong the substrate 4 and transverse to a moving direction 66 of thesupplies and/or to the moving direction 60 of the substrate 4. Thismoving direction is to be evaluated adjacent to the supply.

In use, the precursor gas, the reactant gas, and the purge gas may forma gas bearing between the substrate 4 and the output face 26. Theretothe apparatus 2 may comprise a gas controller for controlling the supplyand drainage of the precursor gas, the reactant gas, and/or the purgegas, thus supplying gasses for forming a gas-bearing layer 69 of the gasbearing between the substrate 4 and the output face 26. By means of sucha gas-bearing layer, the substrate can be separated from the depositionhead. In this way, mechanical contact between the output face 26 and thesubstrate 4 can substantially be prevented. This allows thetranslational velocity of the precursor-gas supply and the translationalvelocity of the substrate to have a different magnitude and/or adifferent direction. In this example, the purge-gas supply functions asa bearing-gas supply 70 for supplying the bearing gas, e.g. the purgegas, between the deposition head and the substrate for forming thegas-bearing layer 69 that separates the substrate and the depositionhead. Thus, in this example, the deposition head comprises thebearing-gas supply, being arranged for supplying the bearing gas towardsthe substrate for providing the gas-bearing layer 69. It may be clearthat, in this example, the purge-gas drain 40 functions as a bearing-gasdrain 72, and precursor drain. It may also be clear that the separationdistance D may be representative for a thickness of the gas bearinglayer between the substrate 4 and a surface of the output face 26.

More in general, the gas-bearing layer in use typically shows a strongincrease of the pressure in the gas-bearing layer as a result of theclose proximity of the substrate 4 towards the output face 26. Forexample, in use the pressure in the gas-bearing layer at least doubles,for example typically increases eight times, when the substrate movestwo times closer to the output face, ceteris paribus. Preferably, astiffness of the gas-bearing layer in use is mostly between 10⁴ and 10⁹Newton per meter, but can also be outside this range. In use, thesubstrate 4 may float against the gas-bearing layer.

More in general, the apparatus may be arranged for applying apre-stressing force on the substrate directed towards the depositionhead. In use, the pre-stressing force increases a stiffness of thegas-bearing layer. Such an increased stiffness reduces unwanted movementout of a plane of the substrate surface. As a result, the substrate canbe provided more closely to the substrate surface, without touching thesubstrate surface. The pre-stressing force may e.g. be applied by a(pre)tensioning the substrate 4, for instance, by a spring guide, suchas a capstan that is pre-tensioned. The spring guide may be somewhatdistanced from the capstans 14. Other ways of applying the pre-stressingforce are possible as well.

In variations of the apparatus 2 in the second embodiment, e.g. as shownin FIGS. 5 and 6, the deposition head may be provided with a cavity 74that, in use, faces the substrate 4. Such variations may, in addition tothe rotatable deposition head 6 of the second embodiment, also relate toa deposition head with a planar or curved output face 26 that is, inuse, moved linearly along the substrate 4 or is stationary positionedwhile the substrate 4 is in motion. A depth of the cavity 74 may bedefined as a local increase in distance between the output face 26 andthe substrate 4. In FIG. 5 this increase in distance equals D₂ minus D₁,wherein D₁ is a distance between the output face 26 and the substrate 4adjacent to the bearing-gas supply 70 and D₂ is a distance between theoutput face 26 and the substrate 4 adjacent to the precursor-gas supply8. More in general, D₂ minus D₁ may be in a range from 10 to 500micrometers, more preferably in a range from 10 to 100 micrometers.

In the examples of FIGS. 5 and 6, the precursor-gas supply 8 ispositioned in the cavity 74 for supplying the precursor gas in thecavity 74 towards the substrate 4. The deposition head 6 may further beprovided with the precursor-gas drains 36 that are positioned in thecavity for draining the precursor gas from the cavity 74. The depositionhead 6 may further be provided with the bearing-gas supply 70 spacedapart from the cavity for supplying the bearing gas at a distance fromthe cavity.

In FIGS. 5 and 6, the curvature of the cylindrically shaped output face26 and the substrate is not shown for clarity. Furthermore, in theseexamples, the precursor-gas drains 36 also form the bearing-gas drains72. It may be clear, however, that, more in general, the bearing-gasdrains 72 may be separate from the precursor-gas drains. The bearing-gasdrains may be spaced apart from the cavity 74, i.e. the bearing-gasdrains 36 may be positioned outside the cavity 74. Thus, in FIG. 6, theoutput face 26 is provided with the plurality of precursor-gas drains36, a plurality of the cavities 74, and the plurality of bearing-gassupplies 70. Depth of cavity 74 can also be zero, which means that thereis no cavity. Precursor gas/region 77A can have gas bearingfunctionality (i.e. stiffness between precursor supply and substrate).

FIGS. 5 and 6 also show the gas-bearing layer 69, which may besubstantially located outside the cavity 74. Flow of the bearing gas inthe gas-bearing layer is indicated with arrows 75. FIGS. 5 and 6 alsoshow a deposition space 77A that extends from the cavity towards thesubstrate 4. Because the precursor-gas supply 8 and the precursor-gasdrains 36 are positioned in the cavity, the precursor gas may in use besubstantially confined to the deposition space 77A. Flow of theprecursor gas in the deposition space is indicated with arrows 78. FIG.6 also shows reactant spaces 77B.

FIG. 6A shows another variation of the deposition head 6 in the secondembodiment. In this variation, the apparatus comprises a selectivelycontrollable laser 79 for reacting the precursor gas on the substrate 4so as to form (or re-form) the atomic layer by selectively controllingthe laser 79. Thereto the apparatus may comprise a laser controller. Thelaser controller may work together with the transportation controller,the driving controller, and/or the pressure controller. In this way, anintended, e.g. predetermined, pattern of an atomic layer or a stack ofatomic layers may be deposited. Controlling the laser may be dependenton the translational velocity of the substrate and the translationalvelocity of the precursor-gas supply. E.g., moments at which the laseris turned on and/or off may be dependent on the translational velocityof the substrate and the translational velocity of the precursor-gassupply. Using a laser may be especially useful in combination with therotating deposition head. A laser may be selectively controlled atrelatively high frequencies that may suit the relatively fast depositionprocess enabled by the rotating deposition head.

FIG. 6A also shows the precursor-gas drain 36. Although not drawn inFIG. 6A, it may be clear that the deposition head may also be providedwith the purge-gas supply 38 and the purge-gas drain 40. More ingeneral, the deposition head may be provided with a plurality of lasers79 or tunable wavelength lasers to induce wavelength-specific reaction.According to the variation of FIG. 6A, the plurality of reactant-gassupplies 42 as shown in FIG. 4 may e.g. be replaced by the plurality oflasers 79.

FIG. 7 shows an apparatus 2 in a third embodiment according to theinvention, in assembly with the substrate 4. The apparatus 2 in thethird embodiment may be provided with the axle 10 and the bearing 12,and may also have the output face 26. In FIG. 7, the moving direction 60of the substrate 4 is directed against the moving direction 62 of theprecursor-gas supply, which may rotate along with the rotatable wheel ofthe drum 5 (the wheel is not shown in FIG. 7 but is shown in FIG. 1 withreference number 5′). In FIG. 7, the substrate 4 is provided along ahelical path 76 around the output face 26 of the deposition head 6. InFIG. 7, the substrate is provided less than once around the depositionhead 6, i.e. around the output face 26 of the deposition head. More ingeneral, the axis of rotation of the deposition head and/or the lengthaxis of the axle 10 of the apparatus 2, may be inclined with respect tothe length axis of one or both of the capstans 14. In this way, it maybe obtained that the substrate 4 is provided along the helical path 76.

FIG. 8 shows an apparatus in a fourth embodiment according to theinvention, in assembly with the substrate 4. In this example, thesubstrate 4 is provided at least once, i.e. between two and three times,around the output face 26 of the deposition head 6 along a helical path76 (e.g. FIG. 7). Or, in other words, the substrate makes at least oneturn, i.e. between two and three turns, around the deposition head 6along the output face 26. As a result, at a moment in time, a first part80A of the substrate 4 that is to be moved around the rotatingdeposition head at least once is located besides a second part 80B ofthe substrate 4 that has moved around the rotating substrate one timemore than the first part 80A of the substrate 4. Here, the term‘besides’ may be interpreted in such a way that the first part 80A andthe second part 80B of the substrate extend along the same imaginaryline 82 that is directed along the first part 80A and the second part80B of the substrate 4 and transverse to the moving direction 60 of thesubstrate 4. A cover (not shown) may be a helically formed shieldstructure following the helical path form of the substrate and coveringthe slit or gap 84 formed between mutually opposed sides of thesubstrate. The shield structure may be formed as a cleanable linerstructure or a sacrificial structure, In addition, suction may beprovided in the shielding structure to remove escaping process gases.

In the fourth embodiment, the apparatus 2 may be provided with aleaked-gas drain for draining the precursor gas that has leaked throughthe gap 84 between the first part 80A and the second part 80B of thesubstrate 4 forming mutually opposed sides 80A and 80B, respectively.

In FIG. 8, positions 88 are indicated along the circumference of theoutput face 26 where the precursor-gas supplies 8 may be positioned. Inthis example, the deposition head 6 is provided with four precursorsupplies 8. As in this example the substrate 8 faces the whole of theprecursor supplies 8, the precursor supplies 8 are not visible in thisexample. Hence, more in general, at least one precursor-gas supply maybe positioned along the circumference of the output face.

As may be clear from FIG. 8, a width W₁ of the substrate 4 may besubstantially smaller, e.g. at least two times smaller, than a width W₂of the deposition head 6. However, alternatively, the width W₁ of thesubstrate 4 may be approximately equal to the width W₂ of the depositionhead 6. This is visible in FIGS. 7 and 9. As another example, the widthW₁ of the substrate 4 may be substantially larger, i.e. at least twotimes larger, than the width W₂ of the deposition head 6. In practice,all such alternatives may form valuable options for deposition one ormore atomic layers.

The apparatus 2 in the first, second, third, fourth, or anotherembodiment, or a variation of one of these embodiments, can be usedaccording to a method according to the invention.

A first embodiment of a method of depositing an atomic layer on asubstrate according to the invention (the first method), comprises thestep of supplying a precursor gas from the precursor-gas supply 8 of thedeposition head 6 towards the substrate 4. The first method furthercomprises moving the precursor-gas supply 8 along the substrate byrotating the deposition head 6. The first method may comprise moving thesubstrate 4 along the precursor-gas supply 8 subsequently to and/orsimultaneously with supplying the precursor gas towards the substrate 4.

In the first method, the translational velocity of the precursor-gassupply is larger than and/or is directed against a translationalvelocity of the substrate. The absolute value of the translationalvelocity of the precursor-gas supply may e.g. by at least 5 times, atleast 10 times, at least 20 times, at least 50 times, at least 100times, at least 500 times, at least 1,000 times, at least 5,000 times,and/or at least 10,000 times larger than the translational velocity ofthe substrate. More in general, it may be clear that if thetranslational velocity of the precursor-gas supply is at least N timeslarger than the translational velocity of the substrate, a stacked layercomprising N−1 atomic layers may be deposited.

The first method may further comprise confining the precursor gas bymeans of the cover 16. Thereto the cover 16 may face the output face 26of the deposition head at locations where the substrate does not facethe deposition head.

In the first method or in another method according to the invention, theseparation distance D (FIG. 2A) between the substrate and the rotatingdeposition head may be maintained. Mechanical contact between thesubstrate 4 and the rotating deposition head may be prevented in thisway. The separation distance D may be substantially constant around atleast a part, and preferably all, of the circumference of the depositionhead. The separation D may be obtained in various ways.

A second embodiment of a method according to the invention (the secondmethod), may comprise attaching the substrate to the carrier 50. Thesecond method may comprise moving the carrier 50 (FIG. 3A/3B) along theprecursor-gas supply 8. In this way the substrate can be kept at adistance from the output face 26 of the deposition head 6. The secondmethod may comprise moving the carrier around the guide 15 along thetransportation face 56 of the guide 15. The transportation face 56 maybe conformal with the output face 26 and is facing the output face 26,so that the separation distance D can be kept constant over at leastpart of the output face 26.

A third embodiment of a method according to the invention (the thirdmethod), may comprise supplying a bearing gas between the depositionhead and the substrate for forming the gas-bearing layer 69 thatseparates the substrate and the deposition head. In this way thesubstrate can be kept at a distance from the output face 26 of thedeposition head 6. The third method may comprise supplying the bearinggas from the plurality of bearing-gas supplies 70 of the deposition head6 towards the substrate 4 for providing the gas-bearing layer.

The third method may further comprise supplying the precursor gas bymeans of the precursor-gas supplies 70 in the cavity 74 that is definedin the deposition head 6 and is in use facing the substrate 4. The thirdmethod may comprise draining the precursor gas by means of the pluralityof precursor-gas drains 72 of the deposition head 6 from the cavity 74.In this way, escape of the precursor gas from the cavity, i.e. flow ofthe precursor gas out of the cavity otherwise than through the precursordrain, may be substantially prevented. In the third method, the bearinggas is preferably provided by means of the bearing-gas supplies 70 at adistance from the cavity. Thereto the bearing-gas supplies 70 may bespaced apart from the cavities 74 along the output face 26.

A fourth embodiment of a method according to the invention (the fourthmethod) may comprise moving the substrate along the helical path 76around the deposition head 6. FIG. 9 schematically shows the movingdirection 60 of the substrate 4 and the moving direction 62 of thedeposition head 6. Tracks 90.i (i= . . . , n−1, n, n+1, . . . ) of acenter 8′ of the precursor-gas supplies 8 along the substrate 4 areshown. A higher index i indicates that movement along that track happenslater in time. The tracks 90.i can be expected to form substantiallystraight lines on the substrate 4. It may be clear that neighboringtracks, e.g. tracks 90.n and track 90.n+1, may correspond to neighboringprecursor-gas supplies 8.

FIG. 9 further shows a length L of the precursor-gas supplies along alongitudinal direction 89 of the precursor-gas supplies 8, that may e.g.be shaped in elongated form. In this example the longitudinal direction89 is aligned with respect to the axis of rotation 91 of the depositionhead, although this is not necessary. E.g., the longitudinal direction89 may alternatively coincide with the length axis 87 of at least one ofthe capstans 14.

The length axis 87 of at least one of the capstans 14 and/or thelongitudinal direction 89 may be transverse, e.g. perpendicular, to themoving direction of the substrate 60. An angle of inclination a may bedefined between the length axis 87 of at least one of the capstans 14and the axis of rotation 91 of the deposition head 6.

A separation S can be defined between centers 8′ of neighboringprecursor-gas supplies 8. In an embodiment, the length L of theprecursor-gas supplies 8 and the translation velocities of the substrateand the precursor-gas supplies, may be chosen such that atomic layersdeposited by neighboring tracks 90.i overlap or abut each other. In thisway a gap between these atomic layer may be substantially prevented.

A reactant-gas supply 42 may be similarly shaped as the precursor-gassupply 8. A location of the reactant-gas supply 42 may be offset withrespect to the precursor-gas supply 8 over a distance R along the axisof rotation 91. It may be clear that the distance R may be adapted sothat a center 42′ of the reactant-gas supply 42 follows a similar track90.i along the substrate as followed by a precursor-gas supply 8 thatneighbors that reactant-gas supply 42. A similar offset can be realizedfor neighboring precursor-gas supplies so that a stack of layers can bedeposited from neighboring precursor-gas supplies. FIG. 9 illustratesthat, as a result of helical arrangements, various possibilities areprovided for coverage of the substrate with an atomic layer. Inparticular, atomic layer stack geometries may be deposited thatdistinguish themselves as a result of their (edge) geometry. Inparticular, a coverage of the substrate near an edge of the substratemay be different from a coverage obtained using known methods.

Hence, it may be clear that a precursor-gas supply or an array ofprecursor-gas supplies may extend along a helical path over the outputsurface. FIG. 9A shows an embodiment of a deposition head 6 of anapparatus according to the invention, wherein a precursor-gas supplyextends along a helical path 76A. FIG. 9A also shows the axis ofrotation 91. FIG. 9B shows a part of a cross-section A-A′ as indicatedin FIG. 9A. A precursor-gas drain 36 or an array of precursor-gas drainsmay extend along the helical path 76A, e.g. in parallel with theprecursor-gas supply 8 or the array of precursor-gas supplies 8. Theprecursor-gas supply and/or the precursor-gas drain may be shaped inelongated form (an array of precursor-gas supplies may be regarded as aprecursor-gas supply being shaped in elongated form). A longitudinaldirection of said elongated form may extend along the helical path 76Aover the output surface, and in this example more than once around theaxis of rotation. Hence, the precursor-gas supply may be shaped inelongated form inclined to an axial direction of the deposition head.Thus, more in general, a precursor-gas supply or an array ofprecursor-gas supplies, and a precursor-gas drain or an array ofprecursor-gas drains, may extend along a helical path. The depositionhead may be provided with a helical cavity 74′. The helical cavity 74′may, in use, face the substrate. The precursor-gas supply 8 or the arrayof precursor-gas supplies 8 may be preferably positioned in the helicalcavity 74′ for supplying the precursor gas in the helical cavity 74′towards the substrate. The precursor-gas drain 36 or the array ofprecursor-gas drains 36 may be preferably positioned in the helicalcavity 74′ for draining the precursor gas from the cavity 74′.

In an embodiment, draining the precursor gas by means of theprecursor-drain 36 may be omitted. The precursor-drain 36 may be absentin the helical cavity 74′ along the helical path 76A or may be unused.Omitting draining the precursor gas through the drain 36 may be enabledby the precursor-gas supply extending along the helical path 76A.Draining of the precursor-gas through the helical cavity may occur as aresult of rotation of the deposition head 6. Such may result from thearrangement of the precursor-gas supply in the helical cavity 74′ alongthe helical path 76A. At an end 74″ of the helical cavity 74′, aprovision for collecting drained precursor gas may be provided.

In a variation the fourth method may comprise, when moving the substrate4 along the precursor-gas supply 8, moving the substrate 4 at least oncearound the deposition head 6. As a result, at a moment in time, thefirst part 80A of the substrate that is to be moved around the rotatingdeposition head at least once is located besides the second part 80B ofthe substrate 4 that has moved around the rotating substrate one timemore than the first part 80A of the substrate, so that the first andsecond part of the substrate extend along the same line that is directedalong the first and second part of the substrate and transverse to amoving direction of the substrate. The fourth method may furthercomprise draining the precursor gas that has leaked through the gap 84between the first part 80A and second part 80B of the substrate 4.

The first, second, third, and fourth method may enable depositing acontinuous stack of atomic layers, i.e. a stack of atomic layers whereina seam between edges of two laterally neighbouring atomic layers may beprevented. However, when carrying out a method according to theinvention, such a continuous stack of atomic layers does not necessarilyhave to be achieved. For example, a fifth embodiment of a methodaccording to the invention (the fifth method) may comprise depositing astack 92 of atomic layers on the substrate, comprises realizing relativereciprocating motion between the precursor-gas supply and the substrate,which reciprocating motion comprises back-turning or reversing adirection of motion between the precursor-gas supply and the substrateat two subsequent back-turning positions. FIG. 10 illustrates the fifthmethod.

FIG. 10 shows the stack of layers 92 and shows subsequent back-turningpositions 94.i (i= . . . , n−1, n, n+1, . . . ). Herein a higher index icorresponds with a later moment in time. In FIG. 10, the layers areshown at a distance from the substrate 4 in order to indicate the momentin time at which they are deposited (indicated by the time axis 96).However, in reality, the various layers 92 will be present on thesubstrate 4 (as indicated by arrow 97), so that a stack of layers willbe obtained with a substantially constant layer thickness 98.

In the fifth method, for example, during deposition the deposition head6 may be rotated back and forth. Optionally, the substrate 4 may also bemoved back and forth, i.e. in opposite directions 60, 64. In this way,the fifth method may comprise realizing relative reciprocating motionbetween the precursor-gas supply 8 and the substrate 4. Suchreciprocating motion may comprise back-turning a direction of motionbetween the precursor-gas supply and the substrate at two subsequentback-turning positions. The two back-turning positions 94.n−1 and 94.ncan be regarded as subsequent back-turning positions, as well as the twoback-turning positions 94.n and 94.n+1.

An atomic layer 92A may be deposited between the back-turning positions94.n−1 and 94.n. This atomic layer 92A may be offset with respect to apreviously deposited atomic layer 92B. This means that an edge 100A ofthe atomic layer 92A deposited between the back-turning positions 94.n−1and 94.n is laterally, i.e. in a direction in which the substrate 4extends, displaced with respect to an edge 100B of the previouslydeposited atomic layer 92B.

As a result of the offset, the edge 100A of the atomic layer 92Adeposited between the back-turning positions is at a different positionfrom the substrate than a main part 102A of the atomic layer 98Adeposited between the back-turning positions.

However, despite the offset, the edge 100A of the atomic layer depositedbetween the subsequent back-turning positions 94.n−1 and 94.n may beadjacent to an edge of an atomic layer deposited between the subsequentback-turning positions 94.n and 94.n.1. The main parts of these layersare similarly positioned from the substrate.

The fifth method may also be carried out by linearly moving thedeposition head 6, instead of a rotating the deposition head 6.

It may be clear from the above and from FIGS. 1-11B that, more ingeneral, a method according to the invention preferably comprises movingthe substrate along a, preferably at least partly rounded, circumferenceof a rotatable drum, in particular of a rotating drum. An apparatusaccording to the invention preferably is arranged for moving thesubstrate along a, preferably at least partly rounded, circumference ofa rotatable drum.

In a generally applicable but optional embodiment, the output faceand/or the drum may, for at least a part of the output face and/or thedrum or for the whole of the output face and/or the drum, have asubstantially cylindrical, conical, or frustum shape or may besubstantially shaped as at least a part of a cylinder, a cone, or afrustum.

The inventors realized that the invention may e.g. be used in the fieldof manufacture of packages. A package may e.g. be packages for food, inparticular packages for beverages. Alternatively, a package may be apackage of a display, in particular an organic light emitting diodedisplay. A method according to the invention may optionally comprisedepositing an atomic layer, preferably a stack of atomic layers, on apackage sheet. An apparatus according to the invention may optionally bearranged for depositing an atomic layer, preferably a stack of atomiclayers, on a package sheet. Hence, the substrate may optionally be apackage sheet. Such a package sheet may be part of a package or may bearranged for forming a package there from. By means of atomic layers, abarrier for gas (e.g. oxygen or water vapour) and/or fluids may beformed on the package. A barrier comprising atomic layers may provide arelatively reliable seal. Leakage through a barrier comprising atomiclayers may be relatively low.

It may be clear from the above and from FIGS. 1-11B that, more ingeneral, an axis of rotation of the deposition head and/or the drum maybe directed along, or may be directed inclined with, the output faceand/or a plane of a substrate surface on which the atomic layer is to bedeposited.

It may also be clear from the above and from FIGS. 1-11B that theprecursor-gas supply may extend, along a curved output face, in adirection along or inclined with the axis of rotation of the depositionhead. This may enable homogeneous deposition of an atomic layer on thesubstrate.

It may be further clear from the above and from FIGS. 1-11B that anapparatus according to the invention may comprise, and/or a methodaccording to the invention may be carried out using: an output face thatextends along and/or over an, at least partly rounded, circumference ofthe drum; a precursor-gas supply that is positioned on an, at leastpartly rounded, circumference of the drum; a precursor-gas supply thatis positioned on an, at least partly rounded, circumference of theoutput face; an output face that is, at least partly, substantiallyrounded around the axis of rotation of the deposition head and/or anaxis of rotation of the drum; a mount for rotatably mounting a drum thatcomprises the deposition head; a deposition head that is part of arotatable drum; a precursor-gas supply that extends over a curved outputface; and/or a deposition head having an axial direction and/or axis ofrotation that is directed along with or inclined to the substrate,wherein an angle of inclination between the substrate and the axis ofrotation preferably is smaller than 30 degrees. Additionally oralternatively, a method according to the invention may comprise:providing the deposition head and/or the drum mounted on an axle, andproviding at least the precursor gas through the axle towards theprecursor-gas supply.

Thus, the invention provides a method of depositing an atomic layer on asubstrate, which method comprises supplying a precursor gas from aprecursor-gas supply comprised by a deposition head towards thesubstrate; having the precursor gas react near, e.g. on, the substrateso as to form an atomic layer, and further comprises moving theprecursor-gas supply along the substrate by rotating the deposition headwhile supplying the precursor gas, wherein moving the substrate alongthe precursor-gas supply comprises moving the substrate along a helicalpath around the deposition head. The invention further provides anapparatus for depositing an atomic layer on a substrate, the apparatuscomprising a deposition head having a precursor-gas supply for supplyinga precursor gas towards the substrate, the apparatus further comprisinga mount for rotatably mounting the deposition head and comprising adriver arranged for rotating the deposition head so as to move theprecursor gas supply along the substrate; said deposition head beingconstructed for having the supplied precursor gas react near, e.g. on,the substrate so as to form an atomic layer, the apparatus furthercomprising a guide having a length axis inclined relative to arotational axis of the deposition head; in such a way as to guide thesubstrate along a helical path around the deposition head.

The invention is not limited to any embodiment described herein and,within the purview of the skilled person modifications are possiblewhich may be considered within the scope of the appended claims. Forexample, the term ‘substrate’ as used herein may refer to a part of aplate or roll that in practice sometimes also is indicated with the term‘substrate’: e.g. the expression ‘moving the substrate along theprecursor-gas supply’ as used herein does not require moving the entireplate or roll along the precursor-gas supply; e.g. the expression‘providing the substrate at least once around the deposition head’ doesnot require that the whole plate or roll is moved around the depositionhead.

As yet another example, the translational velocity of the precursor-gassupply (e.g. indicated by arrow 62 in FIGS. 11A and 11B) may be directedtransverse to the translational velocity of the substrate (e.g.indicated by arrow 60 in FIG. 11A) when the precursor-gas supply islocated adjacent to the substrate. Hence, the axis of rotation 91 of thedeposition head may be aligned with the moving direction 60 of thesubstrate, as shown in FIG. 11A. An angle between the moving direction60 of the substrate and the axis of rotation 91 of the deposition head 6may be in a range from 0 degrees to 90 degrees.

A variation of the example of FIG. 11A is described with respect to FIG.11B, which shows the deposition head in a viewing direction along theaxis of rotation 91 of the deposition head 6. The variation of FIG. 11Bdiffers from the example of FIG. 11A in that the substrate 4 is wrappedaround the deposition head 6.

With reference to FIG. 4, it is noted that the foil 4 traverses only apart of the drum 5 circumference. In the non-traversed bottom partbetween the rollers 14, the two gaseous reactants (e.g. Al-precursortri-methyl aluminum and water vapor) may no longer be separated and bemutually exposed, thus forming an aerosol (“powder”). This particleformation may obstruct the product quality, the process, and the R2Requipment. This is partly overcome in an embodiment with a helical scanfoil motion over the drum (FIG. 8), but may be improved where the‘screening’ of the drum between the foil's roll-off and roll-on zones isnot 100% complete. The cover 16 to prevent any particle (‘dust’)formation may have limitations, as it forms a discontinuity in the gasflow, where both precursors can yield Al₂O₃ particle formation. Inaddition, this enclosure may partially act as a substrate for ALD andCVD of Al₂O₃ which can result in a narrowing gap between the cover andthe drum. This may disturb the control of the drum rotation and thus themachine operation.

To further prevent undesired particle formation, there may be provided aswitchable flow interruption valve system. Examples of such a system areprovided e.g. with reference to the following FIGS. 12-18.

FIG. 12 shows a schematic cross section of an apparatus 2 for depositingan atomic layer onto a substrate 4. The deposition process comprisessupplying a precursor gas from a precursor-gas supply 8 comprised by adeposition head towards the substrate and having the precursor gas reactnear, e.g. on, the substrate so as to form an atomic layer. Thedeposition head is comprised in a rotatable drum 5 and the substrate 4is moved along an, at least partly rounded, circumference of the drum 5.

The deposition head comprised in the drum 5 has an output face that atleast partly faces the substrate 4 during depositing the atomic layer.The output face is provided with the precursor-gas supply 8 and has asubstantially rounded shape defining a movement path of the substrate 4.In particular the precursor-gas supply 8 is moved along the substrate 4by rotating the deposition head comprised in the rotatable drum 5 whilesupplying the precursor gas. Thus a stack of atomic layers is depositedwhile continuously moving the precursor-gas supply in one directionalong a rotation trajectory 62.

The apparatus 2 switches between supplying the precursor gas from theprecursor-gas supply 8 towards the substrate over a first part of therotation trajectory T1 and interrupting supplying the precursor gas fromsaid precursor-gas supply 8 over a second part of the rotationtrajectory T2.

It is noted that the substrate 4 does not cover the entire surface ofthe drum 5. Over the first part T1 of the rotation trajectory thesubstrate 4 may be in proximity to the output face of the drum 5 fordepositing the atomic layer while over the second part T2 of therotation trajectory the substrate is removed or away from the outputface. Thus the said switching may prevent leakage of the precursor gasover the second part T2 of the rotational trajectory. Such leakage mayotherwise e.g. result in an undesired reaction of the precursor outsideof the designated areas on the substrate.

Said interrupting may be provided by redirecting or switching off aprecursor gas flow through the precursor gas supply. This may prevent aleakage of the precursor gas over the second part T2 of the rotationtrajectory 62. The gas supply 8 may e.g. receive gas from a gas source(not shown here) and the switching between supplying and interruptingthe precursor gas supply may be provided by controlling one or morevalves arranged in a gas flow path between the gas supply 8 and the gassource when the precursor gas supply 8 rotates from the first to thesecond part of the rotation trajectory (between T1 and T2).

In the currently shown embodiment, a gas switching structure 103 isformed by electromechanically controlled valves that can be opened andclosed by valve control means (e.g. a controller 101). The valves arearranged in the gas flow path of the precursor gas supplies 8 and thereactant gas supplies 42. The valve control means, in this casecontroller 101, is arranged to close the valves during the second partT2 of the rotational trajectory, at least at positions where thesubstrate 4 does not cover the gas supplies 8 and/or 42. Likewise thecontroller 101 may open the valves when the substrate 4 again covers theoutput face of the drum 5 over the first part T1 of the rotationtrajectory 62, i.e. when leakage may prevented by the substrate coveringthe precursor gas supply 8. Besides valves blocking the ejection of gas,other gas switching structures are possible for affecting the gas flowthrough the gas flow path. For example, the gas flow may also beredirected by opening an exhaust channel that connects to the gas flowpath. Also other means for controlling the gas flow are possible, e.g.by a groove structure acting as a valve system as will be describedlater with reference to FIGS. 15-18.

In the currently shown embodiment of FIG. 12, there is further provideda reactant gas supply 42. The reactant gas, supplied by the reactant gassupply 42, may e.g. react with the precursor gas deposited on thesubstrate 4 by the precursor gas supply 8 to form an atomic layer. E.g.the precursor gas may comprise tri-methyl aluminum (TMA) while thereactant gas may comprise water vapor to form an atomic layer ofaluminum oxide on the substrate. Similar as the precursor gas supplies8, the reactant gas supplies 42 may be provided with valves that mayclose, e.g. under control of the valve controller to prevent an escapeof the reactant gas from the apparatus 2, e.g. at parts T2 of therotation trajectory 62 where the substrate 4 does not cover the outputface of the drum 5. Alternatively, the valves may be provided only forthe precursor gas, e.g. if the escaping reactant gas is notobjectionable, e.g. in the case of water vapor.

In the current embodiment of FIG. 12, the drum 5 further comprises anarrangement of purge gas supplies 38 and purge gas drains 40 a and 40 bthat separate the precursor gas supplies 8 and the reactant gas supplies42. The purge gas drains 40 a and 40 b may also be used to drain theprecursor gas and the reactant gas, respectively, in separate channels.The purge gas may form a gas curtain between the precursor gas andreactant gas that prevents undesired reaction between the two gassesoutside of the designated areas on the substrate 4.

Preferably, the valves are provided in close proximity to the outputface of the precursor gas supplies. In this way, the amount of deadspace wherein precursor gas may remain is limited. Alternatively, if theexhaust point provides sufficient resistance to the gas flow, e.g. by anarrow opening, the valves may be placed further upstream to release aprecursor gas pressure and the gas flow out of the precursor gassupplies is effectively halted. Alternatively or in addition to closinga valve to stop the supply of precursor gas, an exhaust valve may openup to remove any remaining precursor gas in a dead space between theclosed valve and the output face of the precursor gas supply.

It is noted that a problem of undesired leakage of precursor gasses mayalso be partly solved by wrapping the substrate around the drum in ahelical fashion as shown in FIG. 8. Preferably, the precursor gassupplies are switchable between an open and closed state such that atpositions where the substrate leaves the drum, the precursor gassupplies are closed to prevent leakage of the precursor gas at thesepositions.

FIG. 13 shows a schematic cross section of a drum 5 that rotates aroundan e.g. static central axle 10. Precursor gas supplies 8 comprised in anoutput face of the drum receive precursor gas via a gas flow path 155that runs via a circumferential groove 57 a in the axle 10 while gasinlets 8 i are opposite the groove 57 a in a first part T1 of therotational path 62. During a second part T2 of the rotational path 62,the gas inlets 8 i pass an obstruction 103′ forming an end in the grooveof the axle 10 that acts as a gas switching structure to obstruct thegas flow path 155 during the second part of the trajectory T2. In thisway, gas is prevented from escaping the gas supplies 8 during the secondpart T2 of the rotational path 62, corresponding at least to the part ofthe drum 5 that is not covered by the substrate 4.

As shown in the figure, the substrate 4 does not cover the exhaustpoints of the gas supplies 8 in the bottom part of the drum 5 betweenthe rollers 14 a and 14 b. Preferably, the obstructions 103′ defining T2are provided such that a gas supply 8 is interrupted well before thesubstrate 4 leaves the corresponding exhaust point of the said gassupply 8 and turned back on well after the substrate meets again thesaid exhaust point to prevent the undesired escape of gasses, e.g. froma dead space of the precursor gas supply. Additionally or alternatively,a second groove 57 b may be provided in the axle 10 that is connected toa gas drain (not shown). In this way excess gasses remaining in the deadspace of the gas supplies 8 may be drained or at least prevented fromescaping when the supplies 8 rotate along the second part T2 of therotational trajectory 62 thus further preventing the undesired leakageof precursor gas.

FIG. 14 shows another embodiment of the apparatus 2 wherein another gasswitching structure 103 is provided. The gas switching structure 103 isformed by a magnetic valve 101 b that is arranged to slide in and out ofa corresponding opening or valve seat 101 c under control of a valveswitching means formed by control magnets 101 a that are arranged alonga rotational path traversed by the magnetic valve 101 b. The gasswitching structure 103 is arranged in the gas flow path 155 forswitching between supplying the precursor gas from the precursor-gassupply towards the substrate over a first part of the rotationtrajectory T1 and interrupting supplying the precursor gas from saidprecursor-gas supply over a second part of the rotation trajectory T2.Views (A), (B), and (C) show a zoom-in of a magnetic valve system, aview of a control magnet arrangement, and a resulting direction ofmagnetic field lines, respectively.

Accordingly, in an embodiment the gas switching structure 103 comprisesvalves 101 b and valve control means 101 a, wherein the valves 101 b arearranged for affecting the gas flow through the gas flow path 155; andthe valve control means 101 a are arranged for controlling the valves101 b to interrupt the gas flow to the gas supply over the second partT2 of the rotation trajectory 62. In the current embodiment the valves101 b comprise valve magnets and the valves 101 b are arranged forswitching between an open and closed state depending on a polarity of anexternal magnetic field applied to the valve magnets. The valve controlmeans 101 a comprise control magnets arranged along a stationary path ofthe rotation trajectory with an opposite magnetic polarity between thefirst and second parts of the rotational trajectory as shown in view(B).

This reversed polarity results in magnetic fields 101 f shown in view(C) that point in the opposite direction for the first and second partsof the rotational trajectory 62. E.g. in the first part T1, the controlmagnets along the rotational trajectory are pointing with one polaritytowards the magnetic valves for attracting the magnet therein whichfaces the control magnets with one polarity. By this attracting force inthis case the valve is opened and the gas flow path is opened up.Similarly, when the control magnets in the second part T2 of therotational trajectory 62 are facing the valve magnets with an oppositepolarity, the magnetic repulsion may close the valve. In this way thevalves may be switched between the open and closed states when theprecursor gas supply (not shown here) passes a transition between thefirst and second parts of the rotational trajectory 62. It is noted thatwhile a radial magnetic field is shown here, alternatively, the magneticfield may also be e.g. in a tangential direction or any other directionswitching between polarities.

Additionally or alternatively to the shown embodiment, the valves 103may also be opened or closed under the influence of gravitationalforces. E.g. when the valve is in the bottom part of the drum, the valvemay fall down and close the gas flow path and open up again as the drumrotates the valve upwards. This gravitational valve may employ e.g. alsoa system of springs and weights that are adjusted to open and close thevalves at the desired parts of the rotational trajectory.

In an embodiment, of a combined magnetic/gravitational actuation valve apermanent magnet may open the valve in a horizontal position (in a firstpart of the trajectory T1) while in the critical part (the second partof the trajectory T2), gravitation may take over and close the valve. Inthis embodiment, e.g. magnets are provided only over the first part ofthe rotational trajectory T1. It is noted that in general the closingvalve position is preferably close to the reaction chamber, to minimizedead volumes with precursor gas. Note, that also this dead volume can beevacuated by an extra switchable exhaust line.

In an embodiment a ball-shaped or otherwise shaped closing element ofmetal, preferably a permanent magnetic material, etc., may be insertedin the individual radial supply lines that can interrupt the gas flowonce it nears the critical roll-off zone (T2). In a simple form theon-off “actuation” can be by utilizing the earth's gravitational force:when a radial gas supply line in the rotating drum rotates into thecritical roll-off zone T2 the gravitation force will draw the ball overa certain threshold into the closed-off position, until it leaves thecritical zone.

Another embodiment may be that of a closing element with local externalmagnetic force, actuated by an inductive coil, to keep the supply linein its “open” position in its trajectory along the foil, and to switchto its “off” position by reversing the electric current through thecoil.

Another option here is to insert an extra exhaust line (“shunt orbypass”) that can be opened in the “foil roll-off” segment. This casehas the advantage of a continuous precursor gas flow (no pressure drop).

FIG. 15 shows an exploded view of an apparatus 2 wherein the gassupplies 8, 38, and 42 are comprised in a drum 5 that receives gas froma gas source (not shown here) via a sealing piece 55 that seals at leastpart of the drum's surface. In the current view only one sealing piece55 is depicted to show the gas inlets 58 a in the inner drum 51 on thefront side.

In use, the sealing piece 55 will be kept pressed sealingly against thedrum 5 to seal the grooves 57 between the sealing piece and the drumsurfaces thus forming gas flow channels. The sealing piece 55 and thedrum 5 thus form a sealing structure comprising the gas flow channels.The drum 5 is rotatable with respect to the sealing piece 55 andcomprises one or more gas inlets 58. The sealed grooves 57 are arrangedsuch that they lie opposite the gas inlets 58 over a first part of therotation trajectory thus forming a part of the gas flow path. Inparticular the grooves are connected to a gas outlet (not shown) thatprovides gas flow from the gas source through a channel formed by thesealed grooves. On positions where the grooves 57 lie opposite the gasinlets 58, the gas may flow from the gas outlets of the sealing piecevia the sealed grooves into the gas inlets of the drum.

Another aspect illustrated by the current FIG. 15 is a preferred layoutof the gas supplies 8, 38, 42 in the drum 5. In particular, precursorgas supplies 8 are preferably alternated with reactant gas supplies 42separated by purge gas supplies 38. The deposition heads of therespective gas supplies 8, 38, 42 are slit-shaped, e.g. with a width of0.1 mm. Through the slit-shaped deposition heads of the gas supplies 8,38, 42 gasses may flow in a controlled fashion to a substrate (notshown) that may cover part of the drum's surface (see e.g. FIG. 13). Thesaid narrow slit may be formed between exchangeable insert halves 61that are connected to the drum with recessed connection pieces 63. Theinsert halves 61 form an outer part 53 of the drum comprising thedeposition heads of the gas supplies.

A typical outlet gap formed by the insert halves 61 is 0.1 mm in width.A typical insert length is 250 mm for the precursor outlets and 280 mmfor the N₂ inserts. The outer surface of the insert strips is preferablysmooth to ensure an equal gas distribution over the insert length. Thepneumatic restriction of the outlet gap is preferably much higher thanthe resistance of the divider chamber to obtain a homogeneous flow ratetowards de reactant/bearing zone. A homogeneous flow rate is preferredto obtain a homogeneous bearing of the web/homogeneous deposition ofprecursor gasses.

Each gas supply is formed by two insert halves 61 that are positionedagainst each other e.g. with dowel pins and connected e.g. by M3 hexagonscrews. By providing a U-shaped or concave profile in each insert half adivider chamber 61 a is created beneath the gas outlet. A continuousoutlet width over the entire foil size is desired to obtain uniformconcentration and accurate gas separation. Also, smooth outer surfacefor equal distribution over width.

The connection pieces 63 are themselves screwed or bolted to the innerdrum 51 via screw holes 63 a. The connection pieces 63 may thus formrecessed troughs in the drum and comprise gas drain channels 67 throughwhich excess purge gasses and precursor or reactant gas may be removedvia the troughs formed between the substrate and drum.

The combination of a suction force of the drains 67 in the recessedchannels formed by the connection pieces 63 and a pressure provided bythe purge and other gas supplies may be balanced to keep a substrate(not shown) at a desired distance from the drum during deposition of theatomic layers on the substrate. The purge gas supplies may thus functionboth as a gas curtain between the precursor and reactant gasses as wellas a gas bearing for the substrate. The precursor and/or reactant gascan also have a bearing function. Preferably also a circumferentialpurge gas supply 38′ is provided with purge gas to prevent an undesiredleakage of precursor and/or reactant gasses. In addition, as will beshown with more detail in FIG. 16, the grooves 57 may be arranged suchthat a gas supply to the drum is interrupted or redirected when the saidgas supply traverses a part of the rotational trajectory where the drumsurface is not covered by the substrate.

FIG. 16 shows an exploded view of a sealing structure 95 formed by astationary sealing piece 55 that is to be connected to a rotatable feedthrough plate 59 of a drum 55. It is noted that the sealing structuremay act as both a gas transition structure for providing gas fromstationary sources 108′, 138′, 142′ to the rotating drum 5 as well as agas switching structure for interrupting and resuming the gas flow. Thesealing piece 55 comprises circumferential grooves 57 that lie oppositecorresponding gas inlets/outlets in the feed-through plate 59. Thegrooves 57 in combination with the gas inlets/outlets 58 may form avalve 103 that opens as a function of a relative rotation of the drum 5with respect to the sealing piece 55. The drum may rotate around an axle10 that may rest on a bearing structure that may be formed e.g. by aninner cavity of the sealing piece 55 or externally. The axle 10 may bedriven e.g. by a motor (not shown), preferably a heat resistant motor(e.g. brushless DC motor). The motor may connect directly to the drumaxle 10 or e.g. via a gear box to increase torque of the motor

In use, the grooves 57 run between the surfaces of the sealing piece 55and the rotating feed-through plate 59 comprised in the drum 5. Thegrooves 57 corresponding to a first part T1 of the rotational trajectory62 of the drum may be provided with precursor gas 108, purge gas 138,and reactant gas 142 from respective gas sources 108′, 138′, and 142′.In addition, the grooves corresponding to a second part T2 of therotational trajectory 62 of the drum may be connected to gas drains (notshown). In such an arrangement, when the gas inlets/outlets 58 areopposite the grooves connected to the gas sources 108′, 138′, or 142′,the gas supplies of the drums may supply the respective gasses to asurface of the substrate (not shown), during the first part of therotational trajectory T1 when the output face of the drum is inproximity to the substrate. In addition, when the substrate is away fromthe drum's surface, the gas supplies of that part of the surface of thedrum 5 may be interrupted and/or the gasses may be drained to prevent anundesired leakage of the precursor and/or reactant gasses to an externalenvironment.

Accordingly, in the shown embodiment, the circumferential sealed grooves57 extend along the first part T1 of the rotation trajectory 62, endingbetween the first and second parts T1 and T2 of the rotation trajectory62 in such a way that during interrupting supplying the precursor gasfrom said precursor-gas supply over the second part T2 of the rotationtrajectory, the gas flow path that runs via the grooves 57 isinterrupted by a surface of the drum, in particular the feed-throughplate 59 in this case.

Alternative to the shown embodiment, the grooves may be provided in thedrum 5 and gas inlets/outlets in the sealing piece 55. Also, while thecurrently shown sealing piece 55 comprises a plate that seals a side ofthe drum, alternatively, the sealing piece may seal a circumference ofthe drum wherein the grooves are provided along the circumference ofeither the drums surface of the sealing piece. Also combinations ofthese side-sealing and circumferential sealing pieces are possible.Furthermore also the drum 5 and sealing piece 55 may both comprisegrooves or a combination of exhaust channels and grooves. Furthermore,while in the current embodiment, the grooves are shown as having acertain depth, this depth may also be varied along the groove length.

While in the current embodiment only three grooves are shown, thisnumber may be expanded or reduced to fit the particular needs of thedeposition process. In an advantageous embodiment, grooves carryingprecursor gasses are surrounded by grooves carrying purge gas at ahigher pressure than that of the precursor gasses. In this way the purgegas may form a gas curtain between the precursor gas and the externalsurroundings e.g. similar as was discussed in connection with theconcentric tubes of FIG. 1E. Alternatively or in addition, grooves maybe provided with alternating precursor gas 108 and reactant gas 142supplies separated by grooves with purge gas 142 supplies and gasdrains, e.g. in a sequence from the center outward: precursor gassupply, gas drain, purge gas supply, gas drain, reactant gas supply, gasdrain, purge gas supply. In this way the precursor gas together with thepurge gas is drained in a separate drain channel from the reactant gaswith the purge gas.

Alternatively or in addition, precursor gasses may be supplied through asealing piece on one side of the drum while reactant gasses are suppliedon another side of the drum. One or both sides may be provided withpurge gas curtains to prevent the undesired escape of precursor/reactantgasses to an external surroundings. The sealing piece 55 can also have agas bearing to the (axial) drum side.

FIG. 17 shows a schematic cross section gas connections between asealing piece 55 to a drum 5. The drum 5 is rotatable with respect tothe sealing piece 55 over a rotational trajectory 62, driven e.g. by amotor M via an axle 10 that rotates in bearings 12.

The drum comprises precursor gas supplies 8 (e.g. TMA), purge gassupplies 38 (e.g. N₂), reactant gas supplies 42 (e.g. water vapor) andgas drains 40 a and 40 b on an output face of the drum 5. The gassupplies 8, 38, 42 receive gas 108, 138, 142 from respective gas sources108′, 138′, 142′ via a sealing piece 55 that seals at least part of thedrum's surface. Thereto the drum 5 comprises gas outlets/inlets 58 whilethe sealing piece 55 comprises circumferential grooves 57 in itssurface. In other words the grooves 58 follow a tangential path with aradius (distance to the center) corresponding to that of theinlets/outlets 58. In an embodiment, the purge gas lines may be designedin axial direction for gas bearing and separation of the reactant gases,as well in radial direction for bearing the drum extremes.

The grooves 57 are sealed by the drum 5 and arranged such that they lieopposite the gas outlets/inlets 58 over at least a part of the rotationtrajectory 62. In use, a part of the sealed grooves 57 may form part ofa gas flow path between the gas sources 108′, 138′, 142′ and the gassupplies 8, 38, 42. Furthermore, other sealed grooves 57 or another partof the sealed grooves 57 may form part of another gas flow path betweenthe gas drains 40 a, 40 b and the respective gas sinks 140 a′, 140 b′for draining excess precursor gas 8 and reactant gas 42, respectively.Preferably the drain channels for precursor gas 108 and reactant gas 142are kept separate such that no undesired reaction occurs between theprecursor gas and the reactant gas at non-designated areas (i.e. not onthe substrate). As was discussed above, alternative to the shownembodiment, the grooves 57 and gas inlets/outlets 58 may be reversedbetween the sealing piece 55 and the drum 5 or be mixed in anycombination.

In an embodiment the circumferential sealed grooves extend along a firstpart of the rotation trajectory 62, ending between the first and asecond part of the rotation trajectory 62 in such a way that duringinterrupting supplying the precursor gas from the precursor-gas supply 8over the second part of the rotation trajectory 62, the gas flow path isinterrupted by a surface of the drum 5. In this way the relativerotation of the drum with respect to the sealing piece opens and closesa gas flow path between the gas sources/sinks and the respective gassupplies/drains, i.e. the combined structure acts as a valve system. Thegrooves may thus act as valves wherein the rotation of the drum acts asa means for controlling the valves.

The gas feed-through plates or sealing piece 55, may have severalfunctions:

-   -   Connect to the nitrogen inserts and create a nitrogen slit in        circumferential direction    -   Serve as an axle to bear the drum in conventional or air        bearings    -   Provide a larger diameter at the outer edge to fit a        feed-through plate e.g. with a typical diameter of 220 mm.    -   Provide the holes to feed gases through.    -   Serve as an axial (gas) bearing for the drum.

Each chamber/insert is preferably connected with a single radial bore.The outlet chambers may have two bores each. The axial bores serve toconnect to the feed-through plate. The bores may e.g. have a diameter oftypically 6 mm. The radial bores can be e.g. at a distance close to theextreme sides of the drum to minimize the channel volumes and deadspace.

In an embodiment, the drum 5 can be carried by standard air bushings ofporous carbon, and be fixed in axial direction by a flat round airbearing. The drum can be driven by a heat resistant motor M (e.g.brushless DC motor) that connects directly to the drum axle 10 with agearbox in between to increase torque of the motor.

FIG. 18 shows another embodiment of the apparatus 2. The currentembodiment of the apparatus 2 comprises two sealing pieces 55 a, 55 b oneither side of the drum 5. The drum is rotatable with respect to thesealing pieces 55 a, 55 b over a rotational path 62, e.g. rotatingaround an axle 10 that runs in a bearing 12. The first sealing piece 55a is arranged for supplying precursor gas 108 and purge gas 138 to thedrum 5 as well as draining excess purge and/or precursor gas 140 b fromthe drum. The second sealing piece 55 b is arranged for supplyingreactant gas 142 to the drum 5 as well as draining excess reactant gas140 b from the drum 5. An advantage of supplying and/or draining theprecursor gas 108 and the reactant gas 142 via two separate sealingpieces 55 a and 55 b, respectively, is that the two gasses 108 and 142will be prevented from meeting each other e.g. via leaky openings in thesealing piece and reacting at places outside the designated areas.Another advantage may be a smaller spatial claim in the drum design.

In an embodiment there is provided, a switched gas supply lineconfiguration with flow interrupters or resistors fully integrated in acoaxial dual drum set for use in a roll-to-roll ALD system, whereininterruption is done by valves and/or gas feed-through and gasbearing/separation system fully integrated in a force-controlled orshape-controlled configuration.

FIG. 19 illustrates a deposition head 6 which may be mounted on a drum.The deposition head 6 is mounted in a rotatable manner as to enable itto be rotated for example as indicated by arrow 129. A substrate 4 isguided through an entrance point indicated by arrow 122 on to a movementpath that follows the circumference of the deposition head 6. Thesubstrate 4 leaves the movement path in exit point 123 from which it isguided away from the deposition head 6. The guiding unit includescapstans 14 near the entrance point 122 and exit point 123. The capstans14 add tension to the substrate for biasing it, and also bend thesubstrate 4 towards the movement path near the surface of the depositionhead 6. A gas bearing between substrate 4 and deposition head 6 preventscontact between the substrate and the deposition head.

The gas bearing may be provided using any of the gas outlets forproviding a precursor gas, a purge gas, or a reactive gas (the outletnot illustrated in FIG. 19). As will be appreciated, the amount oftension provided using the capstans 14 is limited in order to preventimproper functioning of the gas bearing. If the tension applied to thecapstans would be too large, the substrate may contact the depositionhead at some point along its circumference, which is not desired as thismay cause damage to the substrate.

The solid line 4 illustrates the path of the substrate in accordancewith the invention, a pressure based pulling unit (120 a, 120 b) is usedpulling the substrate 4 away from head 6 near the exit and entrancepoints (122, 123). If only the capstans 14 and the gas bearing would beused without pulling units 120 a and 120 b to maintain contactlessmoving of the substrate 4 across the circumference of the depositionhead 6, the substrate would follow a path indicated by the dotted line4′ in FIG. 19. As will be appreciated, because the amount of tension islimited in view of proper working of the gas bearing, bending of thesubstrate 4 in the direction of the movement path at the entrance point122 without any further guiding may cause the substrate 4 to come tooclose to the surface of the deposition head 6, e.g. when the substratematerial is relatively stiff. This may equally occur near the exit point123 of the substrate 4. To prevent this, alternatively the substrate maybe bent by the capstans 14 using a more gentle bend; however this wouldrequire the exit and entrance point 122 and 123 to be located moreremote from each other. As a result, the surface of the deposition headwould not be used as optimal as with the present invention.

In accordance with the invention, at the entrance and exit points 122and 123, Bernoulli grippers 120 a and 120 b respectively are locatednear the guiding unit 14 to pull the substrate surface towards thegrippers 120 a and 120 b. A Bernoulli gripper uses a high velocity airflow to create a low pressure area at the back side of the substrate,pulling the substrate towards the Bernoulli gripper. Due to the factthat the Bernoulli gripper uses a high speed airflow parallel to thesubstrate surface, contact between the substrate surface and theBernoulli gripper is effectively prevented. The principle of a Bernoulligripper is illustrated in FIG. 20. In FIG. 20, a Bernoulli gripper 120includes a pressurized gas inlet 124. An outlet opening 125 releases thepressurized gas 126 to form a high velocity airflow 127 a, and 127 bparallel to the substrate surface 4. In accordance with the Bernoulliprinciple, a high velocity gas flow 127 a, 127 b (directed away from theBernoulli gripper), causes the creation of a low pressure area exertingpulling forces 128 on the substrate 4.

Back to FIG. 19, as can be seen the Bernoulli grippers 120 a and 120 beffectively pull away the substrate surface 4 from the surface of thedeposition head 6. In addition to this, two forced gas supplies 121 aand 121 b near the entrance point 122 and exit points 123 respectively,opposite the guiding unit 14, apply a further force to the substratesurface such as to keep it away from the surface of the deposition headand to align it to the movement path following the circumference of thedeposition head 6.

The teachings, elements and improvements illustrated in FIGS. 19 and 20may be applied to any of the roll-to-roll atomic layer depositionmethods and apparatuses disclosed in the figures. In particular, theseteachings may be applied to the embodiments disclosed in FIGS. 1, 1E(A),4, 7, 8, 11B, 12, 13 and 15, although they may not explicitlyillustrated in these figures. As indicated in FIG. 19, the improvementssuch as the pressure based pulling units 120 a or 120 b (e.g. in theform of Bernoulli grippers), and/or the forced gas supplies 121 a or 121b may be applied near one or both of the entrance and exit points.Moreover, dependent on the exact specifics of embodiments, such meansmay additionally be applied elsewhere along the movement path to preventdamage.

A further cross section of an apparatus of the invention, in accordancewith an embodiment thereof, is illustrated in FIG. 21. FIG. 21illustrates a beneficial heating system for heating the roll to rollatomic layer deposition apparatus of the present invention. In FIG. 21,the drum 5 carrying the deposition head 6 is manufactured from aanodized aluminum material (preferably an opal-anodized aluminum) or ananodized or opal-anodized alloy of aluminum, such as to provide the drumwith a sufficiently high absorption coefficient for infrared radiation,for example larger than 0.3, preferably larger than 0.8. In the centerof the drum 5 a bore hole 134 is created comprising an infraredradiative type of heating device 131, for example a tungsten-halogenlamp or a silicon carb (SiC) based heater. Also the gas restriction 16may be created from an anodized or opal-anodized aluminum, or an alloythereof. In addition to the heater 131, one or more thermocouples 132are present in the bore hole 134 to allow temperature control in theapparatus of the present invention.

The heating system of FIG. 21 may be applied as a further improvement ofthe roll-to-roll atomic layer deposition method s and apparatuses of thepresent invention. In addition, such a heating system may be appliedindependently in atomic layer deposition arrangements, in view of thesynergies achieved between the radiative type heating device and the(opal-) anodized aluminum elements of the apparatus. Therefore, such aheating device relates in general to an apparatus for depositing anatomic layer on a substrate, the apparatus comprising rotatably mounteddrum, the drum comprising a deposition head having an output face thatin use at least partly faces the substrate and is provided with one ormore gas supplies including a precursor-gas supply for supplying aprecursor gas towards the substrate, wherein the output face has asubstantially rounded shape defining a movement path of the substrate,the apparatus further comprising a mount for rotatably mounting the drumthat comprises the deposition head, and comprising a driver arranged forrotating the drum so as to move the precursor gas supply on the outputface of the deposition head relative to and along the substrate; saiddeposition head being constructed for having the supplied precursor gasreact near, e.g. on, the substrate so as to form an atomic layer; theapparatus thus being arranged for depositing a stack of atomic layerswhile continuously moving the precursor-gas supply in one direction,wherein the apparatus is arranged for moving the substrate along an, atleast partly rounded, circumference of the rotatable drum, wherein thedrum is made of a material comprising anodized, preferablyopal-anodized, aluminum, said apparatus further comprising a infraredradiation type heating system.

The application fields for the present disclosure are not limited to ALDbut may extend e.g. for reel-to-reel deposition equipment for large areamanufacturing of barrier layers for OLED, organic photo-voltaics,flexible organic electronics (e.g. transistors), passivation and bufferlayers thin-film solar cells, moist and oxygen diffusion barrier layersin (food) packaging, etc. and is not limited to the production of Al₂O₃alone. The deposition of other materials (ZnO, etc.), is also envisaged.

Equally all kinematic inversions are considered inherently disclosed andto be within the scope of the present invention. The use of expressionslike: “preferably”, “in particular”, “especially”, “typically” etc. isnot intended to limit the invention. The indefinite article “a” or “an”does not exclude a plurality. Features which are not specifically orexplicitly described or claimed may be additionally comprised in thestructure according to the present invention without deviating from itsscope. For example, the deposition head may be provided with a heaterfor realizing an elevated temperature, for example near 220° C., of apart of the substrate during atomic layer deposition on that part of thesubstrate. As another example, the apparatus may be provided with apressure controller for controlling gas pressure in the cavity, in theprecursor-gas supply, the precursor-gas drain, the reactant-gas supply,the reactant-gas drain, the bearing-gas supply, and/or the precursor-gasdrain. The pressure controller may comprise the gas controller.Furthermore, the apparatus may e.g. comprise a micro-plasma source oranother energy source suitable for enhancing the reactivity of theprecursor-gas material during deposition on the substrate or forpost-deposition treatment after deposition on the substrate. It may beclear that, in addition to or alternative to rotating the depositionhead, reciprocating the deposition head may provide valuable depositionoptions.

1. Method of performing atomic layer deposition on a substrate, whichmethod comprises supplying a precursor gas towards the substrate using adeposition head, the deposition head including one or more gas suppliesincluding a precursor gas supply for supplying the precursor gas; havingthe precursor gas react near, e.g. on, a surface of the substrate so asto form an atomic layer, the deposition head having an output face thatat least partly faces the surface of the substrate during depositing theatomic layer, the output face being provided with the one or more gassupplies and having a substantially rounded shape defining a movementpath of the substrate, wherein the method further comprises moving theprecursor-gas supply relative to and along the substrate by rotating thedeposition head while supplying the precursor gas; thus depositing astack of atomic layers while continuously moving the precursor-gassupply in one direction, wherein method is performed while keeping thesurface of the substrate contactless with the output face by means of agas bearing provided using the one or more gas supplies, and wherein themethod comprises guiding the substrate at least one of to or from themovement path using a guiding unit for bending the substrate having thesurface of the substrate on an outer bend side, and pulling thesubstrate away from the output face during said guiding by using apressure based pulling unit contiguous to the guiding unit opposite theoutput face, for preventing contact between the substrate surface andthe output face near the guiding unit.
 2. Method according to claim 1,wherein the step of pulling is performed using a Bernoulli gripper forcontactless pulling of the substrate.
 3. Method according to claim 1,further comprising a step of creating a gas flow near the outer bendside facing the surface of the substrate using a forced-flow gas inlet,for forcing the surface away from the output face.
 4. Method accordingto claim 1, wherein the gas bearing is provided using the precursor gassupply.
 5. Method according to claim 1, wherein the one or more gassupplies further comprise at least one of a purge gas supply or areactive gas supply, the purge gas supply for supplying an inert purgegas and the reactive gas supply for supplying a reactive gas forreacting with said precursor gas, wherein the gas bearing is providedusing at least one of the precursor gas supply, the purge gas supply orthe reactant gas supply.
 6. Method according to claim 1, comprisingmoving the substrate relative to and along an, at least partly rounded,circumference of a rotatable drum that comprises the deposition head. 7.Method according to claim 6, wherein the drum comprises at least one gasflow channel for connecting the one or more gas supplies with a sealingpiece that seals at least part of the drum's surface, wherein the one ormore gas supplies are provided with gas through the at least one gasflow channel via the sealing piece while rotating the drum relative tothe sealing piece for providing the step of moving of the precursorsupply, wherein one of the drum or sealing piece comprises one or moregas outlets/inlets and the other of the drum or sealing piece comprisesone or more circumferential grooves in its surface sealed by the drum,and wherein during said rotation, for supplying the gas towards thesubstrate, the gas outlets/inlets lie opposite the sealed grooveswherein a part of the gas flow path is formed by the sealed grooves. 8.Method according to claim 1, further comprising a step of pre-heating ofat least one of the gas or the substrate, using a heater which isincluded in at least one of: the deposition head, the one or more gassupplies, or the guiding unit.
 9. Method according to claim 6, whereinthe step of heating is performed using an infrared radiation typeheating system, and wherein the drum is made of a material comprisinganodized, preferably opal-anodized, aluminum.
 10. Apparatus forperforming atomic layer deposition on a substrate, which apparatuscomprises a deposition head including one or more gas supplies, the oneor more gas supplies including a precursor gas supply for supplying aprecursor gas towards the substrate, wherein the one or more gassupplies are arranged on an output face of the deposition head, andwherein the output face has a substantially rounded shape defining amovement path for the substrate over at least part of the output face,such that in use the supplied precursor gas reacts near, e.g. on, asurface of the substrate facing the output face so as to form an atomiclayer on the substrate surface, the apparatus further comprising a mountfor rotatably mounting the deposition head, a driver arranged forrotating the deposition head so as to move the precursor gas supplyrelative to and along the substrate while supplying the precursor gas,for thereby depositing a stack of atomic layers while continuouslymoving the precursor-gas supply in one direction, and a gas bearingprovided by the one or more gas supplies for keeping the surface of thesubstrate contactless with the output face, and wherein the apparatusfurther comprises a guiding unit for guiding the substrate at least oneof to or from the movement path by bending the substrate having thesurface of the substrate on an outer bend side, and a pressure basedpulling unit contiguous to the guiding unit opposite the output face,for pulling the substrate away from the output face during said guidingfor preventing contact between the substrate surface and the output facenear the guiding unit.
 11. Apparatus according to claim 10, wherein thepressure based pulling unit comprises a Bernoulli gripper forcontactless pulling of the substrate.
 12. Apparatus according to claim10, further comprising a forced-flow gas inlet arranged near the outerbend side facing the surface of the substrate, for creating a gas flowfor forcing the surface away from the output face.
 13. Apparatusaccording to claim 10, comprising a rotatable drum that comprises thedeposition head, wherein for providing gas to the gas supplies the drumcomprises at least one gas flow channel connecting the one or more gassupplies with a sealing piece that seals at least part of the drum'ssurface, wherein the sealing piece is connectable to at least one gassource, wherein one of the drum or sealing piece comprises one or moregas outlets/inlets and the other of the drum or sealing piece comprisesone or more circumferential grooves in its surface sealed by the drum,and wherein the one or more gas outlets/inlets and the one or morecircumferential grooves are arranged such that in use, during a rotationof the drum, the gas outlets/inlets lie opposite the sealed grooves overat least a part of a revolution of the rotating drum forming a part of agas flow path between the gas source and the one or more gas supplies.14. Apparatus according to claim 10, wherein a heater is included in atleast one of: the mount, the deposition head, the one or more supplies,the guiding unit, or where dependent on claim 13, the drum, at least onegas flow channel, at least one of the gas outlets/inlets, or at leastone circumferential groove.
 15. Apparatus according to claim 10,comprising a rotatable drum that comprises the deposition head, whereinthe drum is made of a material comprising anodized, preferablyopal-anodized, aluminum, said apparatus further comprising a infraredradiation type heating system.